I am talking of the clear plastic sheet with traces.
I dropped the keyboard into the sea. Transferring from dock to boat, I dropped it into the water, of course it did not work anymore.
I took it apart, rinsed and dried it, but 2 groups of 4 keys did not work.
Looking at the trace and measuring ohms, I found a bad discolored spot with no continuity.

Suggested fixes were rub a pencil over it, that sounded promising but did not work.
So I used a piece of tinned wire out of a PC power supply wire, stipped off the insulation, used a tiny thin strand, cut about an inch long, placed it on a piece of clear tape, and taped it onto the damaged circuit trace.

It worked!

So did plugging it in after it sat in the sun and was still wet inside cause that trace to go open? The damage was about a length of 1/4 inch of discolored trace.

 

May have been corrosion from the salt water.

You can buy conductive trace pens for repairing circuit boards in case your fix stops working.

 

Yes, I looked into that, but my fix was free.
It cost me nothing to break it and nothing to fix it except some time.
Those pens seem very good for repairing and making new traces.

I think rubbing the pencil lead on the existing trace helps with the tinned wire making good connection. The tap I used was clear, not the cheaper translucent tape. and you can push the tiny wire under the tape to help lining it up even after secured to the plastic keyboard sheet.

 

The tap I used was clear, not the cheaper translucent tape. and you can push the tiny wire under the tape to help lining it up even after secured to the plastic keyboard sheet.

Soldering the wire will give a more reliable connection.

If you powered the device before it was completely dry, it could have been that, or corrosion, that caused the failure. Even fresh water could cause problems. Next time, clean the contamination (salt) from the board prior to any repair because salt water will interfere with insulators.

 

You cannot solder that trace without damaging the plastic.
Taping a wire to the trace may work for now but will fail sometime later.
The conductive silver ink is the only solution, IMO.

 

Missed the part where the substrate was plastic, but if it has soldered components, soldering should still be an option.

 

I am talking of the clear plastic sheet with traces.
I dropped the keyboard into the sea. Transferring from dock to boat, I dropped it into the water, of course it did not work anymore.
I took it apart, rinsed and dried it, but 2 groups of 4 keys did not work.
Looking at the trace and measuring ohms, I found a bad discolored spot with no continuity.

Suggested fixes were rub a pencil over it, that sounded promising but did not work.
So I used a piece of tinned wire out of a PC power supply wire, stipped off the insulation, used a tiny thin strand, cut about an inch long, placed it on a piece of clear tape, and taped it onto the damaged circuit trace.

It worked!

So did plugging it in after it sat in the sun and was still wet inside cause that trace to go open? The damage was about a length of 1/4 inch of discolored trace.

BROOO! THANK YOU SO MUCH, I FOLLOWED YOUR STEP AND I SAVED MY BELOVEDKEYBOARD!!! I took a thin wire out off the phone charging cable, and taped it on a ripped plastic circuit keyboard, and boom, it worked! THanks BRO!!