The non-working keys are due to pcb cracking from having dropped it.
No way to fix the PCB, however, you can take it apart, and bridge the pcb cracks by soldering copper wires from the key to the controller directly.
This will return the keyboard to full function..
the PCB is really just a board, with the wires glued onto it, so if the board cracks, the wires may break or become intermittent.
If you intend to DIY fix, Geekhack can guide you through it step by step, All the old guys here have had to fix identical issues on identical keyboards...
LUCKILY keyboards are very simple on the inside.. hahaha
You will need to purchase soldering iron, and solder,