How to Fix iPhone 7 Plus won't turn on
iPhone won't turning on is one of the common problems which can happen to the smartphone. When press the power button on your iPhone 7 Plus – nothing happens. The smartphone doesn’t respond or just shows the Apple logo and the screen remains black. Here is a solution for logic board repairs that can fix this problem. 

Plug an iPhone charge cable to the iPhone 7 Plus to test the iPhone charging current, the charge current jumps around 200mA, and won't stop.

Use 3D screwdrivers to remove the screws next to the iPhone lightning port, and then use LCD opening tools to open the iPhone screen. Remove the iPhone display assembly, disconnect the iPhone battery, and then take out the iPhone motherboard.

Measure the iPhone motherboard with a DC power supply, the standby current is 0, which means no leaks. Trigger the iPhone 7P, the current up to 1.9A, which is large current.

Apply some rosin to the soldering iron, and then use soldering iron to smoke the rosin to the logic board. Supply power to the motherboard, after a while, we can see that the rosin on the area around the iPhone main power IC melted firstly, is the iPhone main power IC damaged?

Login to the zxw dongle to check iPhone 7P schematic diagram, we found that the iPhone Nand flash power supply also in the heating area. Use digital multimeter to measure the iPhone Nand flash, it's short-circuited.

Use BGA graver blade to scratch the power supply capacitor around the iPhone Nand flash, and then apply some rosin to it with LEISTO soldering station, we found C1719 capacitor was shorted.

Use soldering iron to remove C1719, and then use digital multimeter to measure it again, now the data measured is normal.

Assemble the iPhone 7 Plus, press the iPhone power button, now the iPhone 7 Plus can be turned on successfully.

We hope these tips can help you. If your iPhone still doesn’t turn on and it’s a black screen, there may be something wrong with the iPhone hardware. You can go to the Apple Store to fix it. Anyway, good luck.

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