Yesterday I was flashing a ROM using TWRP 2.0 recovery on my HTC EVO 4G. Weird stuff happened during the flash, and I ended up with the TWRP rebooting itself. What followed was a shaky ROM and discovering that I was now S-ON and unable to keep the phone on long enough to do anything about it.
I initially thought it was probably just my EVO's time to die, but what confused me was the reverting to S-ON, the screen going black after a while, and the "5 vibrations of Qualcomm" death. Usually if you get that you're SOL and the phone won't boot at all.
After a bit of asking people if my EVO was indeed dead, I was directed to this thread on XDA and learned that I'm not alone. It seems that TWRP 2.0 is bricking some users' EVO 4Gs due to NAND corruption. This doesn't appear to be a widespread issue (I counted four people in the last five pages of that thread), but if you're using TWRP 2.0 on your EVO 4G, you may want to switch to another recovery while you can.
I've tried stock PC36IMGs, RUUs, changing radios, etc. to no avail. Whatever I do, the EVO boots, runs for 4-5 minutes, refuses to talk to the USB, and then crashes. Now, I've flashed something every day for the past year or two with ClockworkMod, Amon Ra, and TWRP 1.x recoveries and never had an issue, so it's not like I've never done this before.
No fix for the problem appears to be available as of this writing, so take this as a warning and continue to use TWRP 2.0 at your own risk.