Hi all,

sorry for late reply. Had no spare time the last days to work on the printer.

I tried what @o_lampe suggested. I re-soldered the PDN pin so that it protrudes out of the top of the board and then connected the pin to 3.3V. There was no connection to GND. I measured this via continuity.
Unfortunately, this was also unsuccessful. The mainboard no longer started the WLAN module and I was already afraid that I had broken something. However, after removing the VIO connection to the PDN pin, everything worked again.

For no good reason, I then bridged the three solder pads on the underside of the board and soldered the PDN pin the right way round again. In this configuration, at least the enable via M17 works correctly.

I will play around a bit more in the coming days. Specially with the parameters of M569. If I find a solution, I will get back to you.

Otherwise, thanks to everyone who has tried to help 🙂