My current situation with my FP2 is that touch screen is not responding to any thing(whole screen, not just some areas). It works and reacts to buttons but not touch. I noticed that when I start taking back-cover away it starts working again. When I put the cover on it stops.
All this started a 1 day ago when phone froze itself while I was charging it. After some time of no response from screen or even buttons I reset it by removing the battery. After this screen started to act like I described. I opened the case with official support but I also wonder if there could be some advice here.
Never heard of this behaviour before. I just can imagine two possible reasons for that:
Some kind of short-circuit or electrical connection between cover and touchscreen
Touchscreen is not fastened correctly / exactly, thus it might be shifted slightly when attaching the cover and by that causing a bad connection between motherboard’s and display’s contacts.
But what to do?
I would recommend to disassemble and reassemble the display. To me it sounds as well as if there could be a loose connection. Reassembling may thus help.
My touch screen stopped working this morning. As Ivan_Datko describes, except taking the back cover off did not improve (let alone fix) the problem. I haven’t yet looked through the description(s) of how to dismantle the phone, but (after taking the cover off) I did eventually slide the two blue clips in towards the middle, and back again, several times. To my delight, after doing this, once the battery was re-installed the phone worked again, touch screen and all. So this might be worth trying, if you haven’t already.