One month old Macbook Air does not power on I have an almost new Macbook Air. I started to use Time Machine for the first time with a brand new "My Passport" hard drive. I had to unplug it during the process and it was left unplugged for quite some time. Then it went to sleep probably or maybe not, but I plugged it. Then unplugged again (one charger was shared between two Macs).

Cannot turn it on now! The light on the plug cord is green as it is fully charged.
I changed the socket just in case. I tried with USB My Passport drive plugged in and not. Nothing happens.
Keep pressing your power on button for 5 seconds.
The press it again for normal power-up.

You could also try this: Apple Support Page