Chosen Solution

I accidentally scratched the ribbon cable when disassemble the keyboard to remove stuck batteries. It is possible to replace or repair the ribbon..??

Here’s the teardown I did of this type of keyboard to show why it is unrepairable: Apple Wireless Keyboard (A1255) Teardown

Sadly, Apple doesn’t offer any parts for the keyboard. The only hope here is to locate a used one which is likewise damaged and hopefully you can salvage the part from it. Otherwise its time for a new keyboard ;-{