Toad Woes! Immobiliser immobilising!

My 1997 300TDi with a Toad immobiliser isn't starting. When I touch the fob to the immobiliser the LED goes from flashing to solid as normal, the usual ignition and pre-heater lights come on but the engine isn't turning over at all. I can hear a relay clicking behind the dash but having dismantled the dash I can't find any obvious problems. Any thoughts about what to do next?

I had the same issue a while ago..it was the key fob. Do you have another ..
Terry

Just the one unfortunately.

I know I am a bit late to the party, but have you tested the starter motor? I had a similar problem, towed it to the garage and a new starter motor did the trick. And while it was there, I got them to tear out the immobiliser.... horrible things!

Or find alarm fuses and pull, they generally fail safe- ie no fuses it should start