having trouble starting up

[mauricev]

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.

 

[Audit13]

There could be an issue with the trackpad and/or power button causing a short.

Try this: disconnect the battery, disconnect the trackpad from the logic board, connect the charger, don't touch the MacBook. See if it boots on its own in about 30 seconds.

 

[mauricev]

Why do you specifically suggest disconnecting the trackpad?

 

[Audit13]

The power button and keyboard circuitry are routed through the trackpad to the logic board.

 

[mauricev]

You are correct. Does this mean I need to replace just upper case with the keyboard, like one of these, https://www.ebay.com/itm/Genuine-Ap...294301?hash=item260063bf5d:g:t8kAAOSw9ZhbabDL ?

 

[Audit13]

You don't need the entire to case, you can purchase a set of screws, keyboard, and backlight.

 

[mauricev]

Replaced the keyboard. The new keyboard boots, but the left option and left shift keys are permanently depressed. Replaced this keyboard and now the left shift key is ignored. What could be the cause? Two defective keyboards in a row?

 

[Audit13]

If everything works with an external keyboard, the internal keyboard is probably defective.