Hi,
I had this snowy/unresponsive screen issue too.
I was a bit hesitant to use my home oven (it’s really not recommended to use the oven for food after using it to bake electronics).
And I happen to know the owner of an electronics assembly company.
So I asked him if I could place my main board in their SMD oven, and he was fine with it (as long as I took the responsibility for a broken board af course ;-)).
After cooling down the phone booted, but it was extremely slow (like indicated by aborland).
Luckily this improved over time, and after one day it’s almost back to normal.
Only apps I open for the first time after baking it are slow.
So probably all cache was cleared during baking (or because of the fact it has the battery disconnected for almost a full day).
And until now the phone did not show the issue anymore.
So hopefully I can use the phone now for an even longer time (I got one of the first Fairphone 2’s so it’s 5 years old already, and still going strong (running lineageOS 17)
Thanks all for pointing me to this solution!
Jan Pieter