@FlorianK, replacing the PCB with a compatible one won’t damage the drive or your data. It just won’t work. That’s because each PCB stores unique, drive specific, “adaptive” information in flash memory (aka “ROM” or “BIOS”).
These adaptive data need to be transferred from patient to donor. The following PCB supplier includes such a transfer service in the price (US$50):
That said, the symptoms would suggest that there is an internal problem with the drive, not a PCB fault.
I would start by examining the SMART report with a tool such as CrystalDiskInfo:
Look for reallocated, pending, or uncorrectable sectors.
Next I would try to retrieve the drive’s firmware resources with SeDiv:
SeDiv WD Read ROM & Modules:
Depending on what we find, there may be a non-invasive DIY solution.
For more information, visit the HDD Oracle forum:
The Oracle is maintained by people who are dedicated to helping you recover your own data, free of charge, assuming it is possible. I truly hope they can recover your data.