Dead as a dodo

90 would not open with remote, drove it yesterday and no issues. Opened with key, alarm did not go off.
Ignition comes on but final turn nothing seems the immobiliser is preventing engine from starting. Battery fully charged, all fuses OK have gave up. Awaiting for Green Flag to arrive, see if they can figure it out.
Anyone had similar ?
Glasgie

What's the voltage across the battery?

Green Flag turned up battery checked all good
All earths checked, starter motor checked all good
The guy put the key in the ignition and turned it to the III position and pressed the open key fob button,
the red immobiliser light on the dash went out and the defender started.
So he put it down to an almost dead battery in the fob and off he went.
I replaced the battery as directed by the handbook whilst in side the defender.
It made no difference but at least I can start it. No central locking either.
Looks like I'll have to take it to the garage to get checked out, perhaps try my local
before a more expensive trip to the dealer.
Later
Glasgie