I think it's the 244 as it's 2005 year . It's as if ecu is not detecting key so nothing on dash and no crank. I've downloaded a diagnosis procedure so going to take another look tomorrow. As I had to disable the strikeback t aftermarket alarm as it was sounding continuously. But vanbitz the manufacturer of the alarm for motorhomes say it doesn't disable the engine. This is done by the fiat factory fitted system if that makes sense
A key code failure will allow the engine to crank, but the injection of fuel is inhibited, hence the engine will not start. The circuit for cranking the engine is basic, and there are no sensors in that area.
I suggest using a simple 12V test lamp for basic checks. Modern multimeters are very sensitive, and will give a plausible reading through a high resistance.
May I suggest the following test procedure, that I appreciate that you may already be following.
1. Battery OK? It is almost impossible to connect directly to the battery positive, due to the battery mounted fuseboard.
2. Is battery positive clamp firm? For safety, disconnect battery negative when using tools on the battery positive connections.
3. Test between battery positive and engine block (lifting lug?). This to check that engine block is earthed.
4. Carefully remove cover on engine bay fusebox. 2 off M5 nuts, (do not drop behind engine), 8mm box spanner or similar is best tool.
Check between M6 terminal stud, and engine block. This will prove the mega fuse at battery, and connection between.
5. Locate 30A (green) maxi fuse at corner. (See my attached diagram.) Inner end of fuse connects to ignition switch. Test here if possible.
If the above checks are OK, then you have to think about the ignition switch.