I have a Gems car. My Autel Maxiscan OBD works fine with it.
Try the simple things first.
Check the cut out switch hasn’t been bumped accidentally. Try to start.
Does your Engine management light come on when plipper is used and ignition turned with your key?If not try a new battery in it. Do you have a spare plipper?
Next, if these appear ok can you hear the fuel pump when turning the key to first position?
From here it changes to checking fuses/relays.
If these are ok it gets more complex and a compatible OBD unit (or specialist Rover/Landrover) garage should be able to source fault codes.
Are you in the AA or similar with home help? Try them if you are.
The Gems (and earlier Hotwire) systems get signals from many sensors and the ignition module is a good first bet, possibly MAF, and crank position sensor too.
As Ray said earlier low oil pressure could be the cause, especially on a car that has been idle. The oil might have drained from the pump and repriming needed. How often have you run the engine when the car has been laid up?
