Personally and this is just a suggestion since it seems quite a bit easier... Since you already have TWRP installed, rooted and etc. and starting with 5.0 you cannot flash or sideload the OTA through a custom recovery, currently only through the stock recovery as of now.
I would suggest installing a stock unmodified 5.0.1 LRX22C ROM like this AOSP -
http://forum.xda-developers.com/google-nexus-5/development/rom-vanilla-aosp-t2947803
through TWRP instead of trying to update with the OTA package.
Just download a ROM like the above that is flashable through a Current and updated 5.0 TWRP version, like TWRP 2.81,(which is re commended for 5.0+
I haven't updated to TWRP 2.8.2 because I heard that it has some bugs that need to be squashed.
I have been playing around a bit with 5.0+ rom now a couple times. Upgrading from DU 4.4.4 latest build to 5.0.1 and from 5.0 stock and modified stock to 5.0.1 with out any problem's (mostly trying to find a custom rom that I'm content with running as a DD until DU 5.0+ comes out) so I've been experimenting with different ROMs. All of which have ran great so far. If there was a issue at all, it was easily fixed by a Factory Data Reset. (At worst)
First and for most make sure everything is backed up... EFS partition, current nandroid backup, apps TB, Hellium, photos to a cloud or hard drive etc...
Also whenever in recovery Do Not select to wipe "Internal storage/Memory" (internal sdcard) otherwise... Yes you will wipe you internal memory completely! I can't stress and warn you enough.
Download the ROM to your internal storage.
Say in folder named - /sdcard/download/name of ROM zip.
Download the most current SU.zip (believe its 2.40 stable anyway)
http://forum.xda-developers.com/showthread.php?t=1538053
to the same file path as the ROM. Download folder
Ifs It's a AOSP ROM lime the one above, then you need to also download a gapps package to go with the ROM. Download any 5.0+ gapss package... PA, minimal, lollipop, there are a few to choose from.
Lollipop gapps -
http://forum.xda-developers.com/goo.../gapps-google-apps-flashable-package-t2930260
PA-
http://forum.xda-developers.com/par...apps-official-to-date-pa-google-apps-t2943900
Minimal -
http://forum.xda-developers.com/android/software/gapps-google-apps-minimal-edition-t2943330
Youcan google them easily to by just googling N5 5.0 gapps
Remember some gapp packages script will over right and remove the current AOSP installed apps with the ROM, while others will leave both apps on the system.
Its also a good idea to take the opportunity at this point and update your bootloader and your radio version to the newest builds.
You can obtain the new HHZ12d Bootloader and newest radio version in one flashable zip through TWRP recovery from here- thanks to "iammuze" -
https://www.androidfilehost.com/?fid=95857557620393223
Or you can extract the HHZ12D bootloader from the 5.0.1 factory images and manually flash then through fastboot commands and the radio version.
You can also get any of the N5 radio's/modem's versions in img or zip format.
You can get bothThe LRX22C.img or get it in a .zip file from the following link- thanks to "Autoprime"
http://downloads.codefi.re/autoprime/LG/Nexus_5/Modems
the. img is flashed through fastboot commands and the LRX22C.zip is flashed through TWRP recovery.
Now that you have all the files add everything ready to go (including nandroid backup.. etc) Now comes the easy part installing and getting you N5 running 5.0.1.
Boot into recovery mode -
Perform a Full wipe, especially since your coming from a different ROM and OS.
Select - Wipe and from there select (check) System, Dalvic cache, cache, Boot and Data. Perform wipe. Do Not select Internal storage.
Now go to TWRP home page and select install - navigate to bootloader and radio.zip and install.
Go to TWRP home and select reboot recovery.
Once recovery reboots -
Select Install - navigate to your 5.0.1 ROM.zip that you downloaded and Flash the ROM ( it will probably take quite a few minutes, like 5 to 10 mins max)
Go to TWRP home select install and navigate to your gapps package that you downloaded and select to Flash the Gapps package.
Go to TWRP home select install and Flash the 5.0 SuperSU.zip you downloaded.
Reboot system and all should be good.
Install SuperSU from the play store and open the app. If the binaries aren't installed prploperly, then just follow the directions on the SuperSU screen to install them automatically or through custom recovery. Reboot again and done.
I'm currently testing out xTraSmooth 3.1, 5.0.1 build with some modifications and Franco kernel R69 and it is running great so far and battery life seems to be much better. You can find it here -
http://forum.xda-developers.com/goo...lim-1-0-stock-odex-optimized-t2924150/page502
Or you can use command prompt and dowload and extract the. TGZ. File. Then fastboot flash all the images separately, exluding the user data.img. that will wipe your internal storage as well.
Running the allbat.exe runs the use data. img and will wipe the device.... Or us a toolkit like WuFtesh. He just hosted to support 5.0+
http://www.wugfresh.com/nrt/
Anyways... hope this help and clears some things up and I thought I'd share some of my recent N5 4.4.4 to 5.0+ experience's over the last couple weeks!
PS:
If you get stuck in a bootloop a or experience some odd or weird behavior.... Just remember you did just perform a major OS Upgrade and a Factory Data Reset will take care of almost any of you problems.
