I just swapped the mainboard into a new headset piece (speakers power button etc) and the unit works for about 2 minutes and then goes to a black screen. I can hit the power button again and get the device to display three dots, then the screen goes dark again.

Anyone have any ideas? This repair went very smoothly so Im not sure if its overheating now or what.... I did try disabling the prox sensor as well and that did not help.