C5 HDI won't Start

[Alamow]

I have a 2002 C5 HDI that will not start. On connecting Lexia there is only one Fault code in the BSI saying no communication to Alarm.

On checking the BSI parameters the engine immobiliser states Engine ECU locked = yes with the key turn to ign. When the key is switch off the Engine ECU changes to Locked = No.

Transponder label recognized = Yes
BSI Matched to the engine management ECU = yes

Is this likely to be causing the engine not to start?

[Alamow]

I reset the electrical system by removing the battery and following the reconnect instructions posted on this web site. The Info screen came out of Economy mode for a few minutes and displayed a message "Engine Immobiliser Fault". I am not able to access the ALARM via Lexia. The ECU remains in the "Locked state".

I have re programmed the key's into the BSI and the doors lock and unlock using the remote.

Any suggestions?