Part of touch screen not responsive
I have new stock 20a 4.2.2. Then I OTA upgraded to 4.4.2 20d without problem. I used Towel root to root the tablet. The table works fine up to this point. Then I installed TWRP and installed custom ROM. Since then the top part of touchscreen is not response. I used LG mobile support tool to rollback the tablet to stock 20d. But the problem still exists. Any clue?
One side note. I also applied wet screen protector after I installed TWRP. At first I thought it was the problem of the screen protector, but I have peeled it off but the problem still exists.