1. Change different USB ports, and not use a USB hub.
2. Change the USB cable, it's best to use the USB cable that came with the keyboard.
3. Check the cable between daughterboard and the main PCB.

• If it is a JST cable:
• If it is a FPC cable:
• If it is a magnetic connector:

If all of these above don’t work, you can also try unplugging the end that's in the daughterboard and connecting it to the PCB, then plug the PCB end into the daughterboard. The ribbon cables to the magnetic connector are also the same.