Giving command from adb " adb reboot bootloader" but it says "error: device not found".
holding power + vol. down won't do it too.
Read on M7 forums that I should go to a place with bright light, and then try pressing power button for more than 10 seconds. It worked for the person there, but not for me http://forum.xda-developers.com/show....php?t=2460655
Any other way to force reboot it during a reboot? If only there was removable battery :P