I upgraded iOS on my 8 Plus to iOS 12.3 and a day after, the touch became sluggish and 2 days after that touch was complete unresponsive. Reset did not help. My phone is completely useless and has been disagnosed as a hardware issue. All the while though, iOS 12.3 has been running since a downgrade is not possible!
Is anyone else facing this problem? I've been told to pay up a large amount to get a replacement. 🙁