colchiro
Extreme Android User
You need to have a micro sd card installed to flash most custom roms b/c many apps need the card for storage. A 4 gb card will do, but I prefer a 16 gb. (32 gb is the max that will work.) If you're purchasing a sd card, pick up a cheap 2 gb micro sd that you can use for an emergency boot disk, in case you can't boot your NC. How to make a bootable CWM recovery sd card.
There are 3 sections here, depending on your situation. All 3 sections assume you want to replace your stock rom with CM7
1. How to upgrade an existing custom (rooted) rom (CM7, Phiremod, Mirage) on your Nook Color (not sd card).
For users of stock rom, rooted or not, see the section that uses a CWR bootable sdcard (#3).
Wiping data will erase your personal settings on the NC, but not the external sd card, if you have one. If you have apps with settings that you want to preserve, install Titanium Backup from Market. The Pro version allows more than one backup of each app and also simplifies restoring apps so you don't have to tap "install" and "done" after ever one. See my Backup 101 for more info on this.
While you're backing up things, why not make a recovery backup of your current rom, just in case you decide you like that better or there's a problem with your custom rom?
What you need to know before installing:
You will need to install:
FORMATTING DATA: only format data if you want to delete all your apps. Google will still remember your purchased apps and will attempt to download the ones you've downloaded, assuming you have this turned on. See Settings... Privacy... "Back up my data" and "Automatic restore" should both be check for some time prior to installing if you want it to remember your apps and settings. Officially, formatting data is recommended for any rom install. Unofficially, I've had good results just updating my previous rom without formatting data. Your results may differ.
The one exception? You need to format data if coming from the stock B&N rom or from a really old version.
Your rom can be installed from recovery on your NC (boot into recovery from Rom Manager) or by using a separate bootable CWR sd card. This tutorial will cover both installation methods.
An easy way of downloading all this directly to your NC is to purchase Rom Manager from market, less than $6. It will download the latest stable or nightly CyanogenMod rom (or Phiremod) and the latest Google Apps. The files are downloaded to the clockworkmod\download folder on the sdcard. Although this way is easier when it works, you'll need to do the bootable CWR sdcard method (below) if it doesn't.
These are generic images of RM, not necessarily current NC versions:
2. How to install CM7 via Rom Manager (premium).
This is the easiest way to update your rom. If you run into a problem where your NC doesn't boot within 5 minutes or so, you'll need to use the other method (installing via a bootable CWR card) to recover or repair.
The premium version of RM will allow you to download roms directly to your sdcard without removing cards.
There are 3 sections here, depending on your situation. All 3 sections assume you want to replace your stock rom with CM7
1. How to upgrade an existing custom (rooted) rom (CM7, Phiremod, Mirage) on your Nook Color (not sd card).

For users of stock rom, rooted or not, see the section that uses a CWR bootable sdcard (#3).
Wiping data will erase your personal settings on the NC, but not the external sd card, if you have one. If you have apps with settings that you want to preserve, install Titanium Backup from Market. The Pro version allows more than one backup of each app and also simplifies restoring apps so you don't have to tap "install" and "done" after ever one. See my Backup 101 for more info on this.
While you're backing up things, why not make a recovery backup of your current rom, just in case you decide you like that better or there's a problem with your custom rom?
- Open Rom Manager and tap the second option, "reboot into Recovery"
- (To use recovery, up/down volume buttons are used to navigate up and down, press the power button to go back, and press the "n" button to do the highlighted task)
- Press up or down volume button until "backup and restore" is highlighted, press "n" button.
- backup should be highlighted, press the "n" button.
- make sure there are no errors.
- press the power button once if necessary until the "reboot system now" option is available, press the "n" button to return to your rom.
What you need to know before installing:
You will need to install:
- The rom, (stable builds or release candidates are recommended for most users). New versions come out every couple months or so.
- Google apps. This includes Google Play Store, etc.
- Optional overclocking kernels are no longer needed with these builds.
FORMATTING DATA: only format data if you want to delete all your apps. Google will still remember your purchased apps and will attempt to download the ones you've downloaded, assuming you have this turned on. See Settings... Privacy... "Back up my data" and "Automatic restore" should both be check for some time prior to installing if you want it to remember your apps and settings. Officially, formatting data is recommended for any rom install. Unofficially, I've had good results just updating my previous rom without formatting data. Your results may differ.

Your rom can be installed from recovery on your NC (boot into recovery from Rom Manager) or by using a separate bootable CWR sd card. This tutorial will cover both installation methods.
An easy way of downloading all this directly to your NC is to purchase Rom Manager from market, less than $6. It will download the latest stable or nightly CyanogenMod rom (or Phiremod) and the latest Google Apps. The files are downloaded to the clockworkmod\download folder on the sdcard. Although this way is easier when it works, you'll need to do the bootable CWR sdcard method (below) if it doesn't.

These are generic images of RM, not necessarily current NC versions:
Downloading the required files:
As of the time of this post, the latest stable build is 7.2.0, and the latest gApps is 20110828. The latest gApps can be found here. Make sure you always use the version of gApps that matches your rom.
If you want to try a nightly build, the best way to see reviews of nightly builds is to tap "download rom" in Rom Manager, select Cyanogenmod nightly and read the review.
2. How to install CM7 via Rom Manager (premium).
This is the easiest way to update your rom. If you run into a problem where your NC doesn't boot within 5 minutes or so, you'll need to use the other method (installing via a bootable CWR card) to recover or repair.
The premium version of RM will allow you to download roms directly to your sdcard without removing cards.
- To maximize battery performance, make sure your battery is charged to 100% before flashing. I prefer to let it charge during the flashing process.
- Open Rom Manager. Make sure you have the latest version of RM by tapping the top the top item, "Flash ClockworkMod Recover" if your version isn't at the same as the current version (3.2.0.1 as of this post)
- Tap "Download Rom". Tap CyanogenMod. You should get a list of stable Roms.
- Tap latest stable version, which will be the first one (7.2.0). It should give you a notice that's it's downloading.
- Hit back. Tap "Google Apps".
- Tap the latest version, which will be the first one (20110828). Again it should give you notice that it's downloading.
- When everything is done downloading, RM will prompt you to install. Although this will probably work. I prefer to use recovery to install b/c that's the method you'll need to know how to use should you ever need to repair an installation.
- Cancel the prompt to install the rom and tap "Reboot into Recovery" and tap OK at the prompt.
- (To use recovery, up/down volume buttons are used to navigate up and down, press the power button to go back, and press the "n" button to do the highlighted task. Only briefly press the buttons since it's easy to skip a step by holding down a button too long.)
- Press up or down volume button until "mounts and storage" is highlighted, press "n" button.
- use up/down to highlight "format /system", press "n"
- highlight "yes - format", press "n" (always watch for errors)
- when that finishes, highlight "format /cache", press "n"
- highlight "yes -format", press "n"
- IF FORMATTING DATA (see above description. Most people can safely skip this step), highlight "format /data", press "n". (You need to format data if coming from the stock B&N rom.)
- press power button briefly to return to previous menu
- select "install zip from sdcard", press "n"
- select "choose zip from sdcard", press "n"
- select "clockworkmod/" folder, press "n"
- select "download/" folder, press "n"
- select download.cyanogenmod.com, press "n"
- select "get", press "n"
- select your CM rom, press "n"
- highlight "Yes - install... (rom filename), press "n"
- Make sure your rom completed successfully (up to 5 minutes), then flash Google Apps.
- select "choose zip from sdcard", press "n"
- select "clockworkmod/" folder, press "n"
- select "download/" folder, press "n"
- select "goo-inside.me/", press "n"
- select "gapps/", press "n"
- select your gApps version, press "n"
- highlight "Yes - install... (gapps file name), press "n"
- Make sure your gApps completed successfully, then press power button to go back until "reboot" is visible. Select "reboot system now", press "n"
- Let your nook sit for 5 minutes to settle
- If you formatted data, you'll need to do these steps:
- Connect to your wi-fi: drag status bar up from bottom (you'll see a wifi icon on it), choose wi-fi and enter settings. O/W Settings > wireless and network > wi-fi settings
- Set your clock: Settings > Date & Time > Uncheck