iPhone 6 no display after baseband reball
Hi guy/s, I have an iPhone 6 here. No service, no IMEI when dialling *#06#. I was quite positive that the baseband chip has problem, so went ahead to remove the chip. Once the chip removed, I found pads U1 and V1 are both very lose, which confirmed my speculation that it’s baseband problem. As usual I did the jumpers for U1 and V1, and beautifully reballed the baseband chip, then put it back. To my surprise, the phone only has backlight, no display. Removing the baseband chip made no difference. Upon further check, I found pp1v8 line is partially shorted. Resistance is very low on pp1v8 line. Diode mode reading is 0.036, while correct diode reading on a good board is 0.25.
I am very confused. PP1v8 doesn’t run through baseband. How can reballing baseband short the pp1v8 line?
I don’t know if anyone can help please? Thanks.