Hammy,
As far as I can remember, the LED blinks in a sort of 'morse code'. The combination/time period between each 'blink' is an indicator as to what is causing the fault. I'm sure that there'll be details on Aminet somewhere.
Many years ago I had a blinking LED - the sequence indicated to me that it was the keyboard controller chip that had died, but I can't for the life of me recall whether this caused my Amiga (500+) not to boot.
Note down the sequence and have a dig around Aminet - hopefully you'll get lucky and nail the problem.
