Default Bootlooping Issue -- Please help!

I just picked up the HTC One M8 from T-Mo today, and was successfully able to unlock the bootloader with HTC Dev and flash CWM recovery. I tried flashing nV Sense shortly thereafter, and have been stuck in a bootloop since. I tried reflashing the stock recovery, but now I am unable to get back to the bootloader -- I only get the red triangle screen. Does anyone know where to go from here?