I just got my replacement M8 from AT&T yesterday. After obtaining root, S-OFF, and flashing a ROM the phone boots up, goes to the HTC lockscreen for about 4-5 seconds, freezes immediately (ie does not respond to touch) and then proceeds to reboot. This has been going on for the last 24 hours.
Im currently running ViperOne 1.50 with TWRP 188.8.131.52, but I've tried flashing Philz and a few other roms just to see if it is a common occurance and it is.
I'm thinking that I may have to bring it back to the carrier to see if I am able to exchange it. Hopefully I will be, but in the meantime any assistance or insight you guys can provide would be awesome.