The iPhone 6S WIFI module IC short circuit, and it will cause iPhone 6S overheat and high temperature, the final result is that the iPhone 6S won’t turn on. For fix this issue, there are many solutions, here we’ll share a way to fix it without replacing the WIFI IC.
Disassemble the iPhone by phone opening tools, remove the iPhone motherboard, and then connect it to DC power supply to test, after booting for a while（about 10 seconds still not enter the IOS）, it shows large current and power down.
According to the above phenomenon, we suspect that it may be a problem of WIFI（because the current is normal when you start the boot）.
The boot process of iPhone: press the iPhone power button– power IC supply power to iPhone CPU/ iPhone Nand flash/ display IC/ light control IC/ touch IC–CPU start to read the software of Nand flash– start the WiFi part in 10 seconds– start the baseband section in 20 seconds to work. Based on this boot process, we’re judging that iPhone WiFi module is damaged. Because this iPhone 6S can be turned on with iPhone battery and WIFI can be open after booting, it just overheat caused by large current, and then the iPhone temperature is too high.
Use rosin method to make WIFI turn white, and then boot it to test, after a while, the iPhone is seriously overheated. Disassemble iPhone motherboard, observe the WIFI module under the 7-45X Trinocular Stereo Microscope, it’s obviously discolored, which means the WIFI module is short circuit.
Carefully shovel the shell of the WiFi module, measure the diode data of all capacitors with Fluke 15B+ Digital Multimeter, we find a capacitor is short circuit to grounding. Because there are other components connect with this capacitor, in order to find the specific short circuit point, we need apply some rosin to turn the parts in the WiFi module white, and the add voltage on the point of short circuit, after a while, you will see the short circuit parts discoloration.
After confirm the specific short circuit point, we can use CPU Cutting Knife to remove it, and then measure it again, the it’s not short circuit. Install the iPhone to test, everything goes well!