820-01041 Boot Loop


New member
Have a A1990 that is boot looping with no display, possible liquid damage according to customer. Found no corrosion with visual inspection.

Found a short on GPUVCORE_SENSE_N CA669 and was getting heat on GPU and CPU area when i plugged it into charger UA600 was also heating a little, voltage injection not showing heat but i am going to inject again and double check for heat.

QB300 is getting hot when plugged into charger a little heat coming from U3100 area as well.

Customer wants data from the unit and doesn't need a repair, just trying to get this thing into target disk mode so i can get data.

is this one a cooked GPU?

Anyway to isolate the gpu and get the unit into target disk mode or is the GPU required to boot?
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Staff member
I think it should boot lifting GPU core coils.
At least A2141 can do that.

The data can be recovered in DFU mode.
However only authorized repair center can do that; connection to Apple server is required.