31 Jan 2019, 16:48
It's certainly possible that the board was reworked in some way.
I actually purchased another one of these keyboards to resell. When I tested it, I noticed that about half a dozen keys weren't registering. I went into autopilot mode and started desoldering those switches in order to clean the contacts. But when I removed each switch, I found that they were all operating just fine.
It turned out that the keyboard had a dead diode. I replaced the diode and the keyboard worked beautifully.
I didn't know that diodes were at all susceptible to dying. Out of all the many keyboards I've worked on, this was the first time I've come across such an issue.