I have a 2015 MPB 13" that suffered a bad water spill, water pooled on the keyboard for about 5 minutes. I dried it out and it has worked for months but it will not work without being plugged in and it says the battery should be replaced. I'm wary of replacing the battery only to find that it was actually the battery control circuitry that was damaged. Replacing it isn't easy so perhaps I should just continue plugged in. Any advice? Thanks