The issue isn’t with the cabinets, it’s with the floor not being able to expand/contract/float because of the weight of the cabinets on it. How big of an issue this is will depend on the size of the room

Yeah. This started when I stripped down an old Dell desktop that I kept moving around my garage while waiting for an e-cycling day. I’m still trying to decide what to do with the fan (possibly cooking for the enclosure everything is going in).

I’m in the process of doing that to power an old car stereo and amp in my garage. It’s totally pointless, but fun regardless.

The ends of the boards will tell a lot as well. But from this picture they look ok.

I would definitely look into pulling a new wire, and I’d run at least a 5 wire, if not 7, to allow for future upgrades.

Wire resistance what? You understand that wire resistance is going to change based on not only gauge but length, right? Thermostats work the same whether they’re 2’ from the furnace or 200’ from the furnace, both with drastically different wire resistance.

Exactly. It’s a switch. It’s either open or closed; on or off.

That shows the damage but an overall picture would help with a solution.

Ultimately, you may be able to bend it back, but it looks like it’s been overly bent and creased, making it structurally compromised. You’ll need to reinforce it once you get it straightened out otherwise it’s going to happen again.

Alternatively, you may be able to contact the manufacturer, Amazon, or eBay and see if that part is available as a replacement.

right, but OP said gable vent, not box vent.

I'd imagine it depends on how the garage is oriented. You're right that only one vent fan won't work as it needs to pull air from somewhere. Typically a house with gable vents would have one at each end of the house. I'd look to go that route if the garage is situated like that.

I'm not sure what you mean about dealing with shingles, though. Gable vents are in the peak of the end wall, not on the roof.