Time to leave a comment here myself. As far as I’ve experienced, fairphone seems to underestimate this issue - or why is it that I too am waiting more than three weeks on an answer on a simple support request?
I have had similar problems as described here from day one. Now over a month has passed, several attempts & hours of work invested in getting the phone to work - but it is just not usable.
Here the protocol of my latest attempt after letting it sit for two weeks with fully died down battery, inserted a new SIM in slot 1, charge at usb for 30 minutes and unplug.
I start the phone. I am able to use it perfectly fine for a while. I use that time to adjust the touch&hold setting to medium since that had been previously suggested. I try to answer a few of my 400+ whatsapp messages that I am not able to access these days. Aaaand - after what I believe is a very distinct amount of time since switching the phone on, it goes wild. Ghost touches appear all over the screen without me even touching it. There may be reaction to my additional touches, but who knows in that mess. Goes on until I de-activate the screen. And from that point on, when trying to activate the phone again I am not able to get past the lock screen because no reaction to my input whatsoever (no ghost touches either).
This is pretty similar to the last couple times I tried. I have no idea why I can use it perfectly fine for some time and THEN it starts getting unresponsive. Re-mounting the screen did not solve the issue, at least not for good.