Sounds like unrevoked didn't finish correctly, and something was done to either attempt to correct that or something else was done to the stock ROM that shouldn't. No matter the case, it's fixable. You're not likely to be able to save any data at this point though. I'm going to guess you don't care, though if you've already tried to clear storage.
Start with this.
1) Download Clockwork 2.6.0.1 from here:
http://androidforums.com/evo-4g-all-things-root/259446-clockwork-amon-ra-pc36img-files.html
There are instructions in the thread for how to flash it. It's a PC36IMG.zip file that you must rename to PC36IMG.zip, exactly. The trick is that you need to get that file on the root of your sdcard without being able to boot up. You should be able to do so by connecting your phone to your computer, then selecting the option for hboot usb in hboot. You should be able to browse your phone as a drive on your computer. If you have trouble with that, use your card reader.
2) Assuming you can get the file on the card, and follow the rest of the instructions to flash it, verify you can get into recovery by going in through hboot again. You should be taken to a black screen that says clockwork 2.6.0.1 at the top, and has several menu options.
3) Now, you'll need to get a working root ROM flashed. Download this:
Supersonic_3.70.651.1-Deodexed_signed_teshxx.zip
You need to get that on the root of your sdcard, as well. Do not unzip it. You can:
a) Use the card reader
b) Use hboot usb
c) Mount your phone using the storage option in clockwork recovery. Make sure your phone is connected to your PC, just like when using hboot usb.
4) Once you've copied the zip file to the card, make sure you are in recovery, and select the options to wipe data and cache. Go to advanced, and select the option to wipe dalvik cache. Anything that might still be on the phone will be wiped. Just be aware of this.
5) While still in recovery, select the option to install (flash) a zip from the card. Select the zip file you just downloaded and copied over. It will take a few minutes to flash.
6) Assuming the flash is successful, select the option in recovery to reboot. The phone should boot up normally, and you'll be running a new rooted ROM.