Xtremedays
Android Expert
you could try and use adb through your computer.
http://androidforums.com/evo-4g-all-things-root/371191-get-unrooted-warranty-service.html
just substitute the files with the ones that you have.
Unfortunately the files for unrooting revolutionary require the use of fastboot commands. I don't believe that it is an option in anything but hboot .76.
glad it worked. i will need to change the op with the right file.