When connecting up Airport Extreme it flashes green, then amber indicating that it's starting up.
It either now stays on solid amber and never changes or it switches to flashing amber.
You then have no internet connection and no access to airport disks.
An unplug followed by replug/boot up doesn't fix it nor does a press on the reset button.
A solid amber light indicates a possible problem with the AirPort Extreme. Power it off for at least 15-20 minutes.
Hold in the reset button and keep holding it in while you plug the power back in.
Release the reset button after approximately 10 seconds.
After this hard reset, you'll need to recreate your settings in the Airport as it will have forgotten them.
If this does not work after a few attempts, you need to return the device for a replacement.
A blinking amber light indicates a possible problem with the internet connection. You need to check your modem and ethernet cables and/or internet service (it my be an ISP outtage).