How to Fix MacBook Pro Can't Start - (CPU shorted)

“Why my newly bought MacBook Pro cannot be opened?” After understanding some reasons, we believe that the MacBook cannot be turned on, most likely because the MacBook's CPU is shorted, and we need to repair it by replacing the MacBook CPU. The model for this MacBook Pro is A1502, the motherboard model is 820-4924-A.

First of all, test the MacBook Pro. Press the MacBook Pro power button, the MacBook Pro has no response; the MacBook Pro won't turn on. Connect it to the power supply to check the current, there is the charge current.

Disconnect the power supply, we need to disconnect the MacBook Pro battery. Use screwdrivers to remove the screws that fix the rear case of the MacBook, and then remove the MacBook Pro rear case.


Disconnect the MacBook Pro battery, and then connect MacBook Pro to the external power supply via Apple lightning cable, we can see that the current jumps from 0.03 to 0.05. Based on the current tested, we know that the MacBook Pro has a trigger action.

Next remove the MacBook motherboard, and then check MacBook motherboard carefully to see if there is a obviously water-damaged trace or damaged components, there are no obviously failures.

Use VC890D digital multimeter to measure the grounding resistance value for each inductor on the motherboard, when measuring a inductor on the MacBook CPU, the grounding resistance value is 0Ohm, which is abnormal.


Check the MacBook schematic diagram and bitmap, we can see that this inductor is PP1V05_S0_REG, which is power supply inductor.

Now first we need to use soldering iron to pry up the inductor, and then use digital multimeter to measure it. After measurement, we found that the inductor 2 pin rear pole is short-circuited.

Connect a external voltage to the inductor rear pole, the voltage can't more than 1.05V.

After powering up for a while, touch the MacBook Pro CPU with hand, we can feel that the MacBook CPU PCH part is overheat, now we can confirm that the MacBook CPU is damaged, in resulting the inductor L7630 short-circuited.

Protect the components around the MacBook CPU with heat resistance tape, and then use QUICK soldering station to heat the MacBook CPU, next use BGA removal tool to remove the MacBook CPU, finally install the new MacBook CPU.


After replacement, use digital multimeter to measure the inductor L7630 again, the grounding resistance value tested is about 100ohm, which is normal.

Now we need to re-modify the ME on the BIOS data, after re-modification, supply power to the MacBook to check the current, the current jumps properly.

Install the MacBook Pro motherboard and rear case, press the power button, the MacBook Pro can be displayed normally. After few seconds, the MacBook is entered the system smoothly. The MacBook Pro has been repaired!

You may have followed the above steps, but still found that the MacBook Pro cannot be opened, you may need to go to the Apple Store to solve the problem.

 

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