Flashing Red on the side

I’ve had this computer for about two years and all of a sudden it started flashing red on the side last summer and I kind of ignored it cause it wasn’t causing any other issues but now once I come back from college again it started flashing red saying that it wouldn’t charge my battery so then I looked it up as one usually does and it’s like your battery issue all right whatever I got a new battery take it to Best Buy. They’re like well, it’s the motherboard personally I don’t wanna buy a new motherboard. So what do I do now