Your last gasp method of swapping PCBs out may work. However, given the numders you offered as long as the primary frt. number matches, it's the same PCB bit not the version. What version means is usually the updates or any minor improvements during manufacture have gone into the PCB. There maybe a stamped number as well to better ID the version release. No guarantees but in most cases, it will work. However, you're at your own risk. If you had any numbers readable on the burnt component you may ID it in order to know what it did. It seems(WAG) that is was cap or it couldn't handle the surge or burst of electrical imbalance as it were. this is still all a guess if at all this the cause of it not working. It maybe more of the i/f side of the HD or is the true HD running like in steeping control etc.. Again, this is all guess work, at you're playing with it. So expect after all is said and done it's a "go or no go" situation.
I have a WD external drive that has stopped working, having tried all the means suggested to me in order to access it my last hope is to try to replace the PCB.The disk does actually spin up when it's turned on but I hear it pause a couple of times before stopping after just a few seconds.
I put it in a new enclosure and it could then be seen as "disk 7" in disk management but nothing I've tried gets beyond that. It can't be innitialized and that option is now greyed out.
One thing I noticed when I took it out of the original enclosure was a tiny circle of what looked like very fine soot on the metal cover over one of the chips on the board where the USB and power connecters were.This made me think it may have been at some time plugged into the wrong power adapter so the board got fried in which case the PCB may need replacing too.

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