Turn phone on with ADB or Fastboot?

Put the device in charging. When screen turns alive, remove the battery and within 3 seconds, insert it again. Your phone would boot into Android.

Following solution worked for me:

1. Take your battery out (needs to be a charged battery).
2. Press and hold the "Home" + "Volume Down" button. While holding them down plug in the battery. This should get you into Recovery mode.
3. Press "Volume Down" button to cancel Recovery and it should reboot your phone.
   • With my testing you need to have usb charger connected when you plugin the battery.

NOTE: If you have a USB charger connected it may cause boot-loop until you unplug it.

Verified on Samsung Galaxy S3 with broken power button.

Yes, you can turn it on using fastboot.

Enter in fastboot mode, on the prompt type fastboot reboot.

When your phone is not turned on it can't have a adb service running (Disregarding the possible technical difficulties it would also be a security issue.)

Try the following instead: 1. Take out your battery and connect the phone to a charger 2. Your phone should now turn on. 3. Insert your battery.

It worked on my current and on my previous phones (ZTE Blade and Huawei U8220) but it may vary by model and manufacturer.