Chosen Solution
Hi guys, I bought the Macbook Air Mid 2012 (13") battery to replace the faulty battery. Unfortunately, it still says “X” on the battery. Is my MBA motherboard faulty? I did try “SMC” and “PRAM” reset but still not working.
Check and clean the board for liquid damage. Likely the SDA or SCL resistors, which tell the SMC if the battery is present and the percentage (R5380 or R5381). Could be R7006, common to blow too. If you have tried a new battery, will be logic board related. If you have no experience with micro soldering, or don’t have the tools, would recommend sending this to someone.
I would get my hands on another battery to use for testing the macbook - it could be a motherboard issue, or an issue with the charge control circuitry inside the battery pack. If you can’t access another battery, I would take it somewhere that can diagnose your laptop for free so that you know what to replace.
