What to do to extract data on HD when PCB fails and cant find a replacement with exact model/Rev. number

Those pictures appear to be the My Cloud motherboard/backplane not the PCB board on the hard drive itself. Just attach the hard drive to a computer running Linux OR to a Windows PC running a Linux driver and you should be able to pull the files/data off the My Cloud Hard drive.

Here is the backplane of my first gen My Cloud when I was putting an 8TB drive in it. The board the screw driver is resting on is the motherboard/backplane for the My Cloud, it contains the SATA port the hard drive is plugged into.