Chosen Solution
Six months ago I spilled some water over my MacBook. I had just bought it a few weeks before from someone else. I would guess 1/5 of a full glass of water fell, especially over the trackpad. I immediately turned it off and searched for instructions. I opened the back and laid my MacBook upside down on an oven grid and put a fan beneath it. That evening I took everything a part, piece by piece, following the instructions on this website. I found a little bit of water on the battery, and some against the sides, but that was only a very tiny amount. I couldn’t find anything else. I left it open for a while and then put everything back together. Not sure how many hours that was. After that it worked just fine. About two weeks after that I decided to align the trackpad better. I took the battery out, aligned the trackpad, put the battery in and that was it. My MacBook didn’t recognise it. I thought the battery died, so I continued using it while connected to the MagSafe. Today I received my new battery, a Hesker premium, which was the best I could find. But unfortunately my MacBook does not recognise that one either. I followed some troubleshooting I found here, which consisted of taking everything out including the battery and charger. Pressing the power on button for 10 seconds, then putting the charger back in, Then pressing command+option+p+r, etc, something like that. That didn’t help either, unfortunately. The light indicator on the left does not work, even when the battery is disconnected. I understand there are a few possibilities to what may be going on. Are there some I could test at home? Thanks in advance.
Basically, the SMC is not communicating with the battery, which can be an issue with the SMC (worst case), battery indicator, charging IC or data line resistors between the SMC and the battery/charging chip. Try unplugging the battery connector and seeing if the battery is recognised, sometimes this can short the SMC data line for the battery to ground. Personally, it sounds like you may have shorted the solder points above where the battery plugs in (either by unplugging the battery with a metal tool, touching something with a screwdriver or dropping a screw on the board). I have seen people do this a few times, and it basically sends 12V to the SMC, so it no longer recognises the battery. Beyond my advice, you would be looking at logic board repair, which is where it gets more complex to diagnose and fix. If you have a multimeter and the tools required to microsolder, I am happy to point you in the right direction. If not, I would highly recommend sending it somewhere to confirm what is wrong.
