DIY FIX: Drop-damaged iPhone 6 Plus Touch function not working

An iPhone 6 Plus accidentally dropped into the ground, and then the iPhone touch function is not working anymore. According to our repair experience, there are 2 reasons, damaged iPhone screen or damaged iPhone motherboard. First, we need to replace the iPhone screen, if the touch function still not working, then we should check iPhone motherboard.

Remove the scews next to the iPhone lightning port, and then put iPhone on the CPB screen separator, after a while, carefully open the iPhone display assembly, and then remove it. Install the new iPhone display assembly, and then assemble the iPhone. After entering the IOS, test the iPhone touch screen, the touch function is still not working.

Now, we need to check iPhone motherboard. Disassemble the iPhone, carefully remove the iPhone motherboard, and then put it under the microscope.

The bottom of the UMT board is easy to disconnect, first we need to handle the iPhone touch error. There are 2 ways to remove the IC: one is remove it by tweezers; the other one is pry it from the side the IC.

Remove the iPhone touch IC and the re-install it, the iPhone 6 Plus auto restarts when the white Apple appears. Measure the iPhone by DC power supply, the boot current jumps from 300mA.

Take off the iPhone touch IC again to measure the resistance of the bottom of the board by digital multimeter, the resistance value measured is normal.

We didn't meet this problem before, what's the real problem? Because the boot current is larger than normal value, so we are going to measure the boot current after removing the U2 IC, but the problem still there. Measure the resistance value of the bottom pin of the iPhone U2 IC, we found the F4 pin PP3.0V is short circuit.

After check iPhone schematic diagram via WUXINJI Dongle, we know that this circuit has big power, fingerprint power supply and U5411_RF.

Supply power to the iPhone to boot it again, we found the U5411_RF is overheating, remove the 2 components that next to the U2, the iPhone is turned on, we confirmed that this iPhone problem is caused by damaged U5411.

The iPhone boot current jumps from 300mA, the iPhone displays white Apple and won't enter the iOS system. Installing the iPhone touch IC, the new faults comes out after testing, the iPhone has no service and no IMEI after booting.

For this drop-damaged UMT motherboard baseband failure, remove the iPhone baseband CPU, and use QUICK 861DW hot air rework station to solder the jumper wire to V1 and U1.

After soldering the jumper wire, solidified it by painting green UV oil, and then reballing the tin on the iPhone baseband CPU.

Now, install the CPU to the iPhone motherboard, and then assemble the iPhone.

Finally, test the iPhone touch function, now it works perfectly. Continue to test other functions on iPhone, all works properly.