I cant believe PRAM reset worked … Mine stopped working on a very new laptop. I am confident no crumbs or dust was a factor. Turned upside down tapped around no joy. Blowing did not work, paper did not do anything. After few days, decided to give a try to PRAM reset and that worked :) Makes no sense to me but started working right after the reset, give it a try before putting WD40 on it. PRAM reset plug in power and shut off. HOLD Command + Option + P + R, while holding press power few times and you’ll hear a chime.