If it’s running while the jump box is connected by dies when disconnected, it sounds like the alternator is bad.

At that point I’d check one grounded out against the block and check for spark. the sooty look is due to a very over-rich environment.

Have you jumped across the main power at the starter to the solenoid connector?

Spark or timing. Pull a plug, inspect it and then connect it and ground it out to check for spark.

That’s a blowout waiting to happen. Could you drive ON it? Sure, lay it in the road and pilot your vehicle on and over it. Should it be mounted on a vehicle and driven with? Nope.

Next step is checking power to the starter (main power and solenoid lead) and see if jumping across them will turn the starter. If that works, I would start tracking back the solenoid lead.

Since September? You should be fine. Generally you won’t get major degredation until after a year or so from a sealed tank.

Why did you remove the battery to charge it?

you have a 10 A, 12 V fuse (figure it’ll handle about 140 watts total) and you’re trying to draw 300 watts. never gonna work. Yes you can replace with a 30 A fuse BUT the wiring also has to be able to handle 30A at 13.8V From battery to inverter.

An engine change isn’t overly difficult with the proper equipment but it’s much more complex than disconnecting a few things and pulling the motor. It can be quite the undertaking if you don’t know what you’re doing.

Because you would have spent almost 16 grand on a car that sold for 8 grand. Once that issue is fixed, another issue will show up, then another… and another, etc.

Cut your losses now and sell it or scrap it.