The subject is a Zotac 1080 Ti, the previous owner said that this card was water-cooled, but began to disfunction; often crashing with a BSoD after short use, or not booting at all (black screen, cooler was receiving power however).

With no cooler to disassemble, I threw it on the bench and took resistance measurements; as follows:
12v Bus ~ 900 kOhm
12v Ext ~ 900 kOhm
3.3v Bus ~ 700 kOhm
5v Rail 898 ohm ** (in hindsight, this was perhaps too low? oddly close to the reading at 1.8v as well)
1.8v Rail 842 ohm
PEX Rail 117 ohm
Vmem 98 ohm
Vcore 0.3 ohm

then, I left the card on the bench and went to bed.
When I woke up the following morning, I plugged the card into a riser, with hopes of getting voltage measurements at the least. The power supply turned on for a moment, and then automatically shut off (short protection). Odd.

So I took the card out of the riser, and took resistance measurements again; this time the resistances on 1.8V and Vmem seemed to have changed, and were now quite short :(
1.8v Rail was 842 ohm /// *now*: 57.5 ohm
Vmem was 98 ohm /// *now*: 0.5 ohm

Not a good position to be in. The question is; what happened? And where do I go from here?

Just a beginner, please only hit with soft sticks.

See its diagram. This is the "discharge circuit" works. It`s normal.

Look for similar:

I have found the discharge circuit on my card...

But what do I do about it? I apologize if this is a stupid question, I have a lot to learn.

Thanks!

This circuit blocks the supply voltage during transients or accidents.

If this protection prevents you from taking measurements resistance (with the main power OFF!!!) - you must to discharge the C700 capacitor - then the transistor Q535 will be closed and this circuit will not make an error in your measurements.
When working, as soon as a stable voltage of 1.8 V appears, the transistor Q534 opens and discharges the capacitor C700, and then this "discharge circuit" does not interfere with work.

There may be several such "discharge circuits", on several power lines, it depends on the design of the board.