So I had a jailbroken iPhone 5, which were stuck at the loading circle screen the whole night. I then took it in for repair to fix my sleep/wake button today, and now it won't stop restarting itself, even after restoring it to 7.1.2 factory and setting it up as a new phone. It turns on, then in a minute or 2, green lines quickly pops up and shuts it down. Then it turns on again, rinse and repeat. Is my iPhone 5 completely dead? Or is there still hope? Has the motherboard failed me? Is the battery loose?