Keyboard - second try
I removed most of the keycaps so that I could see the bolt heads, then I removed the nuts holding the keyboard together. It was a mistake not to remove all the keycaps, because the keycaps that were in place, made the buckling spring parts come out of their places.
I tested the traces for continuity again, and they were all fine. So I thnk that the problem had been that the buckling spring parts hadn't been seated properly.
I reassembled the layers of the keyboard, but soon found that some of the buckling spring parts had come out of their seatings. So I took it apart again, reseated the buckling spring parts and, without turning the keyboard over, reassembled the layers and put in some of the nuts and bolts.
I think that the test to do then, is to turn the keyboard over so that the buckling spring parts are uppermost, and then shake it slightly to check that they all move freely.
So I put in all the bolts and nuts. The next thing, tomorrow, will be to tighten up all the nuts (I've just bought a 4mm spanner from Hobbyking) and see if everything works.
Here are pictures of the traces. As you can see, the wide connector connects to lines of traces that go up and down, while the narrow connector connects to lines that go from side to side.
Pressing a key, should bring one of the white blobs in the upper picture, into contact with one of the white blobs in the lower picture. The connectors go to a small electronics board, and that knows (by seeing which connectors are connected via the keypress) which key has been pressed, and it translates tat to a scan code that it sends to the computer. Very clever.
You can see in the lower picture where I painted conductive graphite to repair three breaks in the lines. I think those breaks were caused by the water spill that started this whole repair job off.
The egg whisk that you see in the top right hand corner of the picture. is actually the key puller, and it does that job splendidly.