Laser 128 Error (loads fine but behaves like stuck keys)

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Laser 128 Error (loads fine but behaves like stuck keys)
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I purchased a used Laser 128 and just got around to powering it up 3 months later and found it is a bad unit.

I plugged in the power supply and the screen Laser 128 ... came up. Control-reset makes it stop looking for the disk drive content and beeps once like it should but then beep beep beep beep forever while typing random characters.

I put in a disk and it boots and loads fine but after the loading is done it behaves like key is stuck.

I opened it up and disconnected the keyboard completely by the ribbon cable and it behaves the same way.

I disconnected the diskdrive and reattached the keyboard and it still behaves like it has a stuck key (random every time)

If I am fast enough I can get it to type one correct key after I hit control-reset and prints it correctly on the screen. Then it continues to beep and type random characters.

I have come to the conclusion that it is a hardware issue. I blew out all of the internals and removed the mainboard and thoroughly cleaned it and still the same thing.

Any pointers on which part went bad would be appreciated. Overall condition is fine and no jerry rigging or tinkering that I could see. The underside has a few wirewrap blue wires which I assume is factory but I could be mistaken.

I also reseated all of the socketed chips in case there was a bad connection. I'll be keeping an eye open for a good used mainboard for the newer style Laser 128. But I really would like to figure out which part went bad and if someone could give hints or parts they've changed out - would be appreciated.