Chosen Solution
We heard a loud humming noise coming from the next room where this MBA was, and I actually don’t know if it was coming from the attached speakers as I assumed, or from the MBA itself. Moments later it died, never to be woken again. I jumped right to the motherboard solution based on my local repair shop, who doesn’t do this kind of work. But after replacing the motherboard, still dead. I didn’t have any extraordinary difficulties with the transplant, and went slow and careful on the reassembly, so I think it’s unlikely that’s the cause. A bad replacement board is possible but also seems unlikely. So, any other components that would be good candidates for this? Only other symptom besides “dead” would be that the magsafe connector does not light up when plugged in and attached.
I would start off by trying a new charging board, getting a charging light is priority. This part is responsible for the charger to communicate with the logic board, so it knows it is ok to charge. If you are still not getting a light, try the I/O cable. Any other issue with the charging light will be related to the battery or logic board, so disconnect the battery whilst troubleshooting this. Check the MacBook for liquid damage, check the charger port for burn marks and change the charger if it has not been bought from Apple.com, since it will likely not be original and probably caused this if so.
