iPhone 6 Plus touch not working, already replaced touch IC
Hi guys, I have an iPhone 6 Plus here, classic touch IC problem. As usual I replaced meson IC, did the M1 jumper, however it still had no touch. I then replaced Cumulus IC, again no touch. Upon further investigation, I found PP5V7_SAGE_AVDDH line has problem. I tested the line using diode mode, C2414 & C1577 have very low reading: 0.05v. The line is almost shorted (but not fully shorted). I removed Meson IC, PP5V7_SAGE_AVDDH line was back to normal, readings of caps C2414 & C1577 are both correct in diode mode. I thought the Meson IC might be faulty, so I replaced another one. To my surprise, as soon as I installed the Meson chip, PP5V7_SAGE_AVDDH line is shorted. I tried 3 Meson ICs, same result. The line was ok once the Meson chip was removed, but would get shorted as soon as Meson chip installed. The thing is, I already tried 3 Meson chips!
Can anyone help please? Much appreciated.
Update: I just realized that I didn’t explain the problem properly in the initial post above. In fact, the PP5V7_SAGE_AVDDH line didn’t get shorted soon after I installed the Meson IC. The line was fine after I installed the meson chip, however, as soon as I turned on the phone, the PP5V7_SAGE_AVDDH get shorted. After removing meson chip, the short disappeared. However, in the 2nd try (after I powered up the phone), PP5V7_SAGE_AVDDH line would get shorted as soon as the meson chip installed. It looked like something happened to meson chip after I turned on the phone.
Is this a good question?