Trying to revive a WD20EARS-00MVWB0 that has failed

I have read about some seemingly drastic ways to do this, such as physically un-soldering your firmware chip and re-soldering it onto the PCB of a similar (or preferably, identical) drive… Such a measure is apparently made necessary by WD not making the relevant firmware file available to download.
I thought I would try something less drastic first. So my plan at present is to try to source a compatible PCB from a similar WD donor drive. I have found a possible donor drive whose DCM (drive configuration matrix) matches mine precisely. However, the model (MDL) is “WD20EARX…” not “WD20EARS…”
So my question is, is it more important that the DCM values match, or is it essential that first the drive model ‘MDL’ values must be exactly the same? Also, is the ‘DCX’ value relevant in this context, or can it safely be ignored?
Any suggestions or ideas would be appreciated.

Hi, I read once a while back that someone was able to do something like this, however he used a drive with the same model before and after the dash. Other than that I don’t have any other information.