That actually might be better news as a repair might be a simple fix. It can't hurt to visit a repair shop and ask. It might save you a lot of money :-)

Another alternative might be buying a used/refurbished laptop comparable or even better than your current one.

this is definitely a fixable problem, maybe even you yourself could do it
i have a laptop that had a really flimsy power connector, one piece broke off, and the plug went inside when you tried to charge it
i looked up disassebly online (laptops can be tricky) and i tried different thing, tbh i forgot what i did that works now but i think a piece of plastic is holding it in place now, and it's been a few years
also, if it is more complicated, laptop shops can fix a lot of things, even if something needs to be replaced, it not that much without ram

motherboards generally limit the amount of voltage that you can get from the power supply, generally that's 20V. if that component is broken or fully degraded, your best bet is to buy another laptop.

that said, try updating the BIOS if it hasn't been updated recently. It sounds like this is a low-level controller issue then an actual hardware issue.