Apologies for essay but I don't know which parts of the story are relevant. Also please correct me if I'm going about this entirely wrong, I'm learning!
A few months ago my
Seagate SRD00F2 5TB began very quietly clicking when connected to my computer. This clicking was much quieter than the header-click I've experienced with really old drives, either way "Oh god, 5TB of backups down the drain!", devastated.
A couple of weeks after that, I gave it another go but this time it
didn't power up in any way. As far as I knew, it was completely dead, so I took it out of its case thinking the external PSU or some other external element (additional PCB) is burnt out. I connected it via a SATA/USB adapter to my computer, nothing, still dead. I kept the drive in the hopes that one day I'll have time to take another swing at it, so here I am!

I spent most of the last few days researching, and I found that a drive refusing to power up might have a faulty PCB. That's encouraging! So I found a matching
100721570 REV E PCB and ordered the replacement, which is still on en-route. As the BIOS chip will need to be swapped I'm still reading/watching everything I can, as I'm quite out of my depth!
I then read that it might just be a blown TVS diode caused from over-volting/using the wrong PSU or some such. Since I have a spare PCB on the way, I might as well see if there's anything I can do with this one...
When inspecting the PCB under my microscope, not only was the diode circled below shorting, but it was physically cracked. Going off guides, I removed it, cleaned and re-checked the pads and sure enough no more shorting. Great!

I connected it to my PC and my hopes went up when it began to spin! However, it makes
this sound (uh oh, those 4 beeps don't sound normal), then powers off.
I have seen in other threads that damage might have spread to the 2x zero-ohm resistors circled below, but they're reading as shorting/0... which is what we expect, right?

I don't know what the two circled below are, but they're also reading as shorting. Again, I don't know if that's what I want??

TLDR; An external drive stopped working. Originally beeping very quietly, several weeks later refusing to power up. I removed a blown TVS diode and the drive it now spins to life, but won't stay powered. It makes
this sound then powers down. Does anyone have a clue what could be wrong?