A time ago I acquired an interesting scientific calculator SHARP EL-9000 to my collection.
But as I expected the flipping keyboard did not work at all. The reason for that was broken connections on the flex PCB where it is being bent. I tried to fix it with the conductive glue but it didn't work.
So I decided to recreate the whole new flex PCB. I removed it from the aluminium board, scanned it and used as background in the KiCad to be able to create original traces. The Chinese PCB manufacturers offer relatively cheap flex PCB services so I sent them data of finished PCB.
And this is the result. I was very satisfied with it.
So I installed the new flex to the calculator and tested its functionality.
The keyboard works perfectly.
Now I am also able to use the printer CE-50P compatible with this calculator. Before the fix it wasn't possible because to start printing you have to press OPTION button which is located on the flipping keyboard.