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Hello, I am trying to repair a 5s for a customer. The phone does not turn on They have been to an iphone repair facility previously who mentioned that it needed a u2 replacement My diagnostics attempt.

  • The battery was dead,

  • I charged the battery and connected the 4 terminals as shown in the picture and the battery

  • I pressed the power button for about 30 seconds

  • The phone did not turn on and became very hot and 2 generic locations on the board

Is there any other way I can diagnose the board or make the iphone turn on ? Thanks Image Link http://i.imgur.com/l0D97dQ.jpg

What you’re describing is a U2 (Tristar) chip issue. If you replaced the charging port and put in a good battery and the phone doesn’t turn on or charge then the U2 chip needs to be replaced which is underneath the shielding were it gets very hot that you mentioned in your picture. It requires a skilled person that knows microsoldering to replace the chip. I hope this helps you answer your question.