Chosen Solution
I have a iPhone 5s with boot looping and appears a red screen. I know that can be a lot of problems, but I don’t know how can I test and find the problem. I have a multimeter and a soldering station. I already have removed the motherboard. And now, I d’like to test with the multimeter if is some problem in the tracks of the front-facing camera. And if not, how can I test the Tristar or the worst case the NAND.
You should rule out a parts issue before moving on to the logic board. You haven’t told us what diagnostics you did before removing the board like. · Disconnected front flex assembly · Disconnected home button. · Replaced screen. · Replaced battery. · Tried a hard reset. · Tried an update · Restored the phone. Once you know it isn’t a parts problem you can move onto the board. You could test Tristar with a Tristar tester or you can diode the dock connector and compare readings to a known good board. As for the NAND I would see if any errors came up in iTunes while doing an update or restore.
