Chosen Solution
My IPhone is not turning on after jailbreaking with checkrain but I made a huge mistake by unplugging my IPhone before it was done jailbreaking.
Have you tried forcing the phone to restart? To do so, in quick succession press and release volume up, then volume down, and then press and hold the power button. Keep holding until you see the Apple logo, then let go. This shouldn’t take much more than 10 seconds of holding the power button.