iPhone 6 Plus touch screen not working- how to fix?

The iPhone 6 Plus touch is not working, becuase it doesn't response to the touch, how to fix it? 

First, we try to fix it by replacing iPhone touch screen. Use phone open tools to disassemble the iPhone, remove the iPhone display assembly, and then install the new iPhone display assembly. After replacement, power on iPhone and test the iPhone touch screen, it's still not working.

Now, we need to check iPhone motherboard. 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 iPhone, press the iPhone power button, after entering the IOS, touch the iPhone touch screen, now it reponses smoothly.