HP-41C - Memory lost

[Vintage63]

Hello again and thank you for your inputs.
My 41C has S/N 2052A00467 so it was built in the USA, A, in 1980 the last week, 52, of that year.

I'm not too keen to open it with the risk of braking what still look sound. I believe it is a 'full nut' as the cornner of the display are at right angles.

I have just pressed the case of the 41C on the top left corner of the dsiplay and the LCD behaves like every LCD when pressed, broken posts?
Other ideas?