Previously, both Fastboot mode and Recovery mode were accessible only from the bootloader menu. But now you can boot directly into Fastboot a.k.a Download mode by pressing the “Power + Volume down” buttons, the combination which was previously used to boot into bootloader mode. So how do you boot into bootloader mode now?
÷ BOOTING INTO HTC ONE M9 BOOTLOADER MODE
1-Power off your phone.
2- Press and hold “Power + Volume Down + Volume UP” for a few seconds until you see the bootloader menu.