Red power indicator

I just tried it without being plugged into the mains, it works fine and shows me the battery charge percentage. I then plugged it into the mains and the LED that was off turned red.

Ok, thanks for your help.

Yes! I think some cells in your battery are damaged.
It barely holds or doesn't hold a charge at all.
You need to replace it if you want to use your laptop unplugged, otherwise your laptop will quickly shut down, lasting only a few minutes maybe.

--
Who loves learning! finds knowledge that comes from reflection!
P.S. Frequently create a restore point! It solves a lot of problems.

That's typical.
A battery can show 94% while in reality, it's almost empty.
I have a battery that indicates 83% and only lasts 2 to 3 minutes.

--
Who loves instruction! Find the knowledge that comes from reflection!
P.S. Often create a restore point! It solves quite a few problems.

Anyway, your battery is damaged and no longer charges.
You need to shut down your PC using the Shut Down function, and once your PC is off, then unplug it and do not pull the plug while your PC is running, otherwise you risk your PC not restarting.

--
Who loves instruction! Find knowledge that comes from reflection!
PS. Frequently create a restore point! It resolves quite a few issues.

Try using your laptop on battery power and see if your battery drains after a certain period, or if the percentage remains the same.

--
Who loves instruction! Find the knowledge that comes from reflection!
PS. Frequently create a restore point! It solves quite a few problems.

I just tried without being plugged in and the battery drains quite quickly.