Do you mind to point me the solution you came up with? I also spent countless hours on that.
Bound and determined to come up with a workable solution, I wasted a completely unreasonable amount of time on these drives. Unfortunately I was unable to find a way to recover any functionality without erasing the drives or source any firmware which proved to be stable. Samsung and their vendors eventually shrugged their shoulders and told me to go pound salt (regarding drives I purchased both through eBay and directly from authorized dealers).
I think I ended up with 18 PM963’s.. To be honest, I threw them on a shelf and forgot about them. I no longer use any Samsung drives unless doing so is absolutely unavoidable.