The keyboard and trackpad are not recognised at all on my 13" A1278 2012 MacBook Pro, which is odd as the power button still works without issue. Everything else functions normally, except that the keyboard and trackpad are completely unrecognised (no mouse movement at all, no keys work).
I have tried a PRAM reset using a USB keyboard, running Apple Diagnostics (which found no issues whatsoever), I've cleaned the logic board thoroughly with isopropyl and a toothbrush (the MacBook had suffered liquid damage, got it second hand), and I have tried replacing the trackpad and cable (which remained completely unrecognised, it is now in another MacBook and works 100%).
I have also tried installing a fresh copy of Yosemite to no avail.
Is there a component which controls the input from the trackpad and keyboard? Both the keyboard and trackpad connectors on the motherboard appear completely fine, and the power button works without issue.
Any advice would be greatly appreciated,