110 key / immobiliser issue help

I’d be grateful for any wise words regarding a 2014 110 starting issue please:

The fob failed to cancel the alarm and when the engine start is attempted the starter motor turns over and the engine appears to run for up to one second, sometimes less. Applying throttle makes no difference. I’ve replaced the fob batteries and attempted various permutations of the described resynching procedure, eg standing outside and pressing the lock button 4,8,12 times etc. No joy.

So yesterday, after trying for over a week, got the EKA code. Performed the manoeuvre exactly as per handbook twice - still no change.

I’m wondering if this is consistent with an immobiliser remaining activated, or would that prevent the engine firing at all? There is definitely fuel in it!

I’ve yet to try disconnecting the battery or checking the fuses (fuel pump etc) and will do so tomorrow along with any other suggestions? Otherwise I’ll look forward to the hell of pushing it through a ten point manoeuvre out of the cramped carpark with an access too low to permit a recovery truck….

Thanks in advance for any constructive advice!

To stop a diesel engine, you take away the fuel. To take away the fuel you have a solenoid on the fuel pump which stops the flow.
The solenoid needs 12V to 'open'.

Could it be the emergency shut off ??

Appreciate the comments. Disconnecting the battery for an hour did the job, presumably clearing a fault code. Clearly I am a dumbass, but at least I learned to add a spanner for the terminals to the standard tool kit….