Chosen Solution
A family member spilled water on this macbook air a few months back and gave it to me yesterday. They had turned it on, and while it does boot up and the keyboard and trackpad work, the screen is at a very low brightness, as if the backlight is broken, and will occasionally flicker between brightness settings, but always staying very, very dim.
Michael Gorman , Stop charging or powering up your device until the liquid damage is addressed correctly, as you could be shorting out components inside the Macbook. You really should take care of the corrosion that is happening inside the device from the water damage as that could be your problem. A tear down link for your device Link #1, disassembly guide will enable you to get inside the device to remove the damage/corrosion caused by the liquid. Use the 2nd link as a guide/instruction on how to clean/repair the device from liquid damage. After this you will be able to power on the Mac and see if further damage has to be addressed. 3rd link is to more disassembly guides if needed. Good luck. I hope this helped you out, if so let me know by pressing the helpful button. MacBook Air 11" Early 2015 Teardown Electronics Water Damage MacBook Air 11" Early 2015 Repair
