Chosen Solution
Trackpad only clicks, does not move cursor ever. Keyboard will type, but it is intermittent. Like in the manner of it will type for one second and not for one second and continue on and off… Key commands at startup don’t always take, I can almost always get the SMC to reset, NVRAM reset takes a couple tries sometimes. Should o replace both? No idea where to go. Tried going into system preferences under keyboard (with USB mouse) and the option to use fn for f1 or f2 ect flashes one second on one second off. Very weird haven’t found anything similar. Any ideas? Update (12/23/2019) Tried checking a few things on logic board, cables etc nothing obvious. If someone knows of a few things to check on logic board I am capable just have no idea where to start.
It does sound like you had a liquid spill at some point either damaging the keyboard and trackpad or the cables are damaged with corrosion. When you use an external USB or Bluetooth keyboard and mouse do you encounter any difficulties? Also did you try running the on board diagnostics? restarting the system pressing the D key? Did you get any error messages? Reference: Mac startup key combinations
