I am beyond stumped. I am a mac certified technician and was working on my personal early 2015 12 inch macbook. The screen needed to be replaced so i replaced it. shortly after the keyboard and trackpad is not recognized at all. Only power button works. So I replaced the trackpad cable. nothing. i then replaced the topcase. nothing changed. I have no idea what this could be. Tried resetting smc or nvram and nothing either. any suggestions would be grateful and thank you!