I suspect that either contact error or problem with the responsible IC.
I was able to replace the LCD on the housing of my T90, the entire unit with the display and IC underneath.
Checking my little T90 family, I saw that one family member was having problems with her display on the top of the case. When the camera was switched on, but also every time any button was pushed or the selector wheel was turned the display showed signs and symbols that did not match the...
You would have to see if you can get to the place, maybe
@Laurent can take a detour there?
Unfortunately I don't have a T90 open right now.