Macbook Air 13" mid-2013 (running macOS Sierra) with no USB devices plugged in (except a Logitech wireless mouse that I never have plugged in while the laptop boots up).
- I receive the message
USB devices disabled: unplug the device using too much poweronce upon startup or logging in even when nothing's plugged into the USB ports.
- The built-in keyboard and trackpad sometimes stop working. I suspect a logic board failure of some sort (but I'm no expert on hardware). However, they are always working upon starting up the machine, but only fail occasionally once I'm logged in to my user account.
These issues only started after recently recovering from a water spill (so that may have something to do with it). The laptop was dried with a fan for 5 days and works well still otherwise.
Here is one of the messages Console gives me:
default 08:11:00.752541 -0500 kernel 000790.147865 HS02@14200000:
AppleUSBHostPort::interruptOccurred: **overcurrent detected with port status 0x4000**, localSimulatedInterrupts = 0x0
How I've tried to fix it
I have taken it to the nearest Apple Store and had a Genius Bar employee run diagnostics. They told me that there were no apparent hardware issues, and that I would have to send the Macbook to a repair factory if the issues persist.
After cleaning the PCB with Q-tips and rubbing alcohol to remove any visible residue/dust, the keyboard/trackpad issues do not occur as often. However, they still happen once in a while.
I have also reset the SMC and NVRAM multiple times to no avail. I also deleted my Preferences.plist file as a friend suggested a corrupt Preferences.plist file can cause issues with the keyboard and trackpad.
What can I try to fix my issues? I think these issues are probably a result of the water damage, but repairs can go up to $750 USD (so I was told) and the Genius Bar employee could not tell me what specifically was wrong with my Macbook. I would like some more info before I go and dump another few hundred dollars onto this thing, because if I have to pay $750, it may be more worth it to go and buy a new laptop instead.
TL;DR by @owlswipe
My Macbook's trackpad and keyboard spontaneously stop/start working after some water damage, and the USB ports spontaneously shut off too. What's the cheapest way to get this thing back into working order?
This is what happens upon logging back in after a restart: