回答“HTC One M9 in weird boot loop”I just went through this with my M9 and it looks like the linked Youtube video is down. :/ [For this, I'm assuming the phone is S-On and the bootloader is locked. It also assumes that the eMMC chip hasn't hit it's End-of-Life and died] The answer starts off with getting the right aosd.img for the phone. Then, with the phone in fastboot mode and connected to the PC: Type "fastboot flash aosd aosd.img" and press Enter. This will give you back Download Mode. From there, the choices are: If the bootloader is OK, you can boot the phone into Download Mode and try to re-flash the firmware using the official RUU .exe. [If the bootloader isn't OK, the phone may go into a reboot loop: To break the loop, hold the Power and Volume Up buttons] If you are unsure of the bootloader, you can try reflashing the phone by putting the RUU .zip file onto a micro SD card and flashing from Download Mode. The worst case scenarios I've seen so far are: If the phone cannot be reloaded via the RUU and you're stuck S-On, you can use...