HP 48GX weird boot loop problem - any ideas?

[wmundstock]

Hi All.
Here is a weird problem on a HP48GX.

https://youtube.com/shorts/gmMI6rGGFSU

Have you ever seen something like this?
Any ideas of what the problem might be?

I am thinking could be a problem with the contacts of the keys. Maybe some solder broken...
If I boot a working calculator and get to that screen where it asks for the memory reset, when I click any buttons I get that beep.

If I move or twist the calculator while its beeping I notice some slight variation in the frequency of the beeping.

The problem is that these beasts are very hard to take appart and even harder to bring back together... any ideas?

Thank you