MacBook Air early 2015 given me to check out. With the keyboard power button, boots every once in a while. When booted, the keyboard is dead, not even capslock. One thing I noticed is that with the battery disconnected and I press the power button, the light goes green for a moment then reverts to amber, but it only rarely boots. I tried shorting the power pads and nothing, but here's the real weirdness, when the laptop is opened up upside down, it will periodically bong as if it's about to boot, but rarely does. Could this be liquid damage? Aren't there detectors for that? How to know if they've been tripped? It's not clear if is damage to the i/o board or to the logic board or both.