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iPhone motherboard current fluctuation

Hello! I got an iPhone 12 that does not turn on. No visible damages, no breaks, no water damage. Took it apart, connected to a dc psu, no current draw without booting. With trying to boot, it starts to draw a weird amount. It fluctuates between .400 and 0, with like 2 different spikes starting from each end, getting close to the other end, then back, and the cycle continues. Here's a vid about it:

https://youtu.be/BXc8cXyvBLs

It doesn't get hot (at least not on the upper side of the board), my sandwich heater didn't arrive it yet, and I dont want to take it apart unless it's necessary. Any ideas what could be wrong here?

Any help is appreciated!
Have a nice day!

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any shorts around nand ?

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A short around the nand would cause symptoms like that?

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@abel11493 its possible, check for low resistance on caps

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And what do I do, if I find more than one shorted caps? Meaning that the line is shorted, but how do I find the faulty cap, or the other source of the short? Perhaps if it doesn't generate outsanding heat, it could be under the nand, like 2 solder balls joined together?

por

@abel11493 you would need to inject voltage and either use ipa, rosin or freeze spray. failing that a thermal camera

por

There are more then one shorted lines. Mostly around the PMIC. The PP1V2_IO, PP_SRAM_S1, PP_CPU_PCORE, PP_CPU_SRAM, PP_SOC_S1, PP_AVE_S1

PP_CPU_ECORE(this one has like 0.3 ohms to ground)

PP_GPU has ~12ohms to ground.

How is this even possible?

Now when I try to boot, it the current jumps up all the way for a fraction of a second, then back to 0. When I let go of the button, it jumps up again, but then back to 0 again. If I repeat this quickly a few times, the PMIC gets really hot around H4 pads. Is the PMIC faulty? Or is it something else?

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