Have you tried flashing the Sprint 6.5 rom from
http://www.htc.com/us/support/touch-...int/downloads/
Otherwise, task29 will wipe your phone totally clean. Put it in bootloader, let it establish a connection to your PC and then run task29. It will be a very quick flash, after which you need to flash a new rom (you need to be unlocked for all of them except the 2 shipped Sprint roms)