Before you read any further, this is for S-Off Verizon HTC One M8 devices only! Do not flash this RUU unless your M8 is S-Off. RUU stands for Rom Update Utility and has always been the preferred method for flashing HTC devices back to stock as well as unbricking HTC devices. There is still no RUU available to return your device to full on stock, however developer "dotta" has built an RUU for S-Off devices that will return your device to stock 1.55.605.2. This is a prerooted Rom. This RUU compiles the current boot/hboot/system/recovery/radio/firmare images. This will wipe your phone's internal memory entirely just like a normal RUU file. You will want to be sure to backup any important data prior to flashing this RUU. The preferred method for flashing this RUU is through fastboot. Simply drop the file into your fastboot/adb directory on your PC, boot your phone into fastboot mode, then type a few commands. Head to the link below for the download and full instructions.
Via XDA
