Re: Where no Range ROver should ever have to go
Alternatively, just try getting 6" of wire with a spade connector at each end, and jump the power-pins (not coil-pins) on relay 16 in the underbonnet fusebox. Relay 16 is the relay closest to the centre of the fusebox. Energising relay 16, is essentially what the BECM does, when you turn the ignition key to pos III.
If you can't get it to crank using your screwdriver on the starter, then I'd check the BIIIG wires that join the battery/starter (also refer electrical sticky). If the resistance of these wires is nearly zero (=good), then I'd be looking at a starter problem. If it cranks using the screwdriver-on-starter method, but not when jumping RL16, then I'd think it could be an internal failure in the fusebox.