Also had the same problem on a 5C. shorting pins worked. However reassembling and power cycling still did not bring it to life. I raised the pins a bit, no effect. What worked was shutting the phone off, then powering it back on by holding home and power. The apple logo appeared, disappeared, then reappeared while holding down both home and power. I released the buttons, let the phone boot up and all is well! I figure this is some sort of hard reset process with the phone off.