I tried to power the raspberry pi though the GPIO pins. I had a 3.7 volt battery charging board that outputed 4.2 volts.
I connected it to 5v and ground on the raspberry pi and the lights were a litle dim so I dicided to connect it to 3.3 volts and ground, thinking it should not make a difference big since the charger is made for 3.7 volt batteries. The lights were now really bright and I heard a high pitched sound.
Now the pi does not boot and the red and green lights are solid
Edit: I have a raspberry pi 2 - I probed the GPIO pins snd they are still outputing the correct voltage so maybe ther is still hope.