Some things to try:
Shake or bump it around a little and see if it comes back on. This could indicate an intermittant connection somewhere.
open the box to see if you see any solder joints look gray and grainy which would indicate a poor connection that need to be reheated. (cold or sometimes called dry solder joint).
Disconnect and reconnect any connectors you can find.
In any event it seems you have something going on with the circuit that lights the led since it still seems to be working.