Chosen Solution
Spilled liquid on left side of keyboard. Here’s what’s wrong: Laptop screen has faint horizontal lines and intermittently freezesKeyboard and Trackpad stop responding 50% of the time, usually after sleep Aside from that, no other problems at all. No problems on an external display, so I assume that rules out the integrated graphics card? Do I need to replace the logic board, or is it something else?
Remove the logic board and clean it with 95%+ isopropyl to get rid of any corrosion. When the bottom cover is removed, check for corrosion on the top right of the board (where the screen plugs in). If there is none here, it is likely liquid has gotten between the plastic hinge cover to the screen itself. Keyboard and trackpad issue are likely a problem with the trackpad cable. If the trackpad is not detected by the Macbook, the keyboard will not work as well. I have seen this intermittent fault before on non-liquid damaged MacBooks.
