Chosen Solution
I have a MBA early 2015. It seems to work normally but battery discharges even when in sleep mode even when powered off completely (about 20% during the night). I took out the logic board and noticed this capacitor has blown. Can it be the main cause of the battery discharge? I do not have a heatgun now but I have a donor board, only little scared to work on otherwise working logic board.
That cap belongs to battery charging circuitry and being blown may be partly shorting the power line causing the issue. Try removing it somehow, a soldering iron would be safer than hot air if you have no experience. Evaluate if drain stops after removal and if that’s the case you should be done. However I’d recommend replacing the capacitor even if the board should work without it too.
While swapping out the logic board will likely fix your logic board issue you may still have an issue with your MacBook Air 13" (Mid 2013-2017) I/O Board as well.
