After removing the bottom plate, you can remove the PCB with just two screws. To remove the connectors, using a set of pliers can be useful.

In my case, this PCB was broken. At first I thought the Sanyou SRD-S-124DM relay was broken, but after some more investigation, I found that the board was not producing DC voltage any more.

For now I've given up fixing the PCB and could not find a replacement yet, but I found another "quick" fix, see next steps.

If you find a replacement PCB, just plug all the plugs back in the right place and replace the two screws. Don't forget to replace the sheet of plastic as well.