One of the problems with the HTC EVO 3D—whether rooted and trying out new kernels/ROMs, or unrooted and trying buggy software—is the occasional lockup. With the EVO 4G you just had to pull the battery and move on. You can pull the battery out of the EVO 3D too, of course, but there's another way to force it to power off in the form of a "3D finger salute" (trademark pending).
You may have noticed when you got your 3D that unlike the EVO 4G, the volume buttons are not on a rocker. They are two separate buttons next to each other.
Next time you're locked up and don't want to remove your case, pop off the phone's back, and yank the battery, try this:
- Press and hold the power button and both volume buttons at the same time for five to eight seconds.
As far as I can tell, this also bypasses the HTC Fast Boot program (not to be confused with fastboot.exe or the fastboot stage of booting), so if you are about to flash a new ROM and just want to get out of your old ROM without having to locate and turn Fast Boot off, you can pop out of running mode pretty quick by holding down these three buttons.
This also appears to work regardless of whether the lockup is related to the kernel, IO (overclock, undervolt), or an app.
If you have a super duper protective case on your EVO 3D that practicallly requires a blowtorch to take it off, this method could be your new best friend.