Car not starting

[Xanderx67]

Had my 350 off the road for about two months while I had the clocks out to have the LED's changed. During this time I have attempted to start the car but it just cranked and didn't fire up. I replaced the original battery for an Optima one thinking that would sort the issue out. It didn't.

Then I thought maybe the removal of the clocks may have been the problem so waited for their return and fitted them back in. That didn't work either.

Replaced the keyfob batteries in case they too had died. Didn't work.

Got the AA out to try and get it going. There for about two hours trying everything. Did a diagnostic check on the car and came up with these errors:

 

Patrol found the following fault code/s:
System : Engine control - 31E / ECCS 2P1212 - Traction control. Error Message : Malfunction.P1610 - Immobilizer. Error Message : Faulty operation.P1612 -
Immobilizer. Error Message : Faulty operation.*U1001 - CAN communication. Error Message : Faulty

 

Any ideas? While it was standing I had a CAN Bus KMH to MPH Speedometer Converter fitted so this may be the issue. It was fitted as per instructions so It may not be.

 

Has anyone got any definite ideas? It was running fine before I removed the clocks so cannot think of any reason why it shouldn't now.