I bought a MBA 11" as not tested, and it does not charge, or show any led on the charger. How ever, when i disconnected the interconnect cable to the I/O board and connected the charger, the charger lit up green. After i reconnecter the interconnect cable and plugged the charger back in, the green led lit up and faded shortly after. I checked the charger with my MBP 2015 13" and it works flawlessly. what could cause this behavior?