Issues after liquid spill

Hi,

got issues with my MacBook Air after I dropped coffee over.

I left it drying for 5 days and disconnected the battery. Cleaned up everything with rubbing alcohol.

It turned on again but very slowly and only with power cable connected. I resetted SMC and PRAM and now it stays dark.

I know everything could have broken after the spill, but is there a way to verify that it's not the battery. Without knowing, it does not make sense to purchase a new one.

Maybe it's possible trying to run the Macbook with battery disassembled to verify?

Thanks for your help!

Jens