Question Laptop battery at 80%, does nothing.

Apr 17, 2021
So I've had this Acer Aspire v3-571g for maybe 5-6 years or so.

Good little runner, slower than a turtle on drugs, but does what I want it to.

I've replaced the battery once in it's life, about 2-3 years back and it was working fine, fast forward 2 years of no use, sitting in the cupboard ( Yes I left it in, like a muppet )

It will start fine, when it is plugged in, it shows me it's charging and at 80%, but this never changes, it's always 80% and 1 minute until fully charged.
But the second i take the cable out it turns off.
I have left it charging all day today and still it's the same, works fine without a battery inside, cable runs it fine.

Going to assume it's broken, i've run through all the steps i can think of:

Reinstall the windows driver.

Check it's it cable or battery ( runs fine with the cable )

Unplugged it, held power button down for 30s and left it half hour and turned it back on.

^--- Only get basic info, tells me the battery is in pretty good health, think it was ( 46xxx /5xxxx ) last charge, would have to do it again to be sure.
The only thing that catches my eye is:
Platform Power Management Capabilities: PCI Express Active-State Power Management (ASPM) Disabled
PCI Express Active-State Power Management (ASPM) has been disabled due to a known incompatibility with the hardware in this computer.

Now i'm not an amazingly technological person, so I have no idea if it could be the issue.

Any ideas would be greatly appreciated, perhaps I can save buying a new battery.
I'm not really in a rush, just giving this to the mother in law to watch movies on basically, but she's like a teenager, wants something portable and wire free to watch in bed.