2004 Elite 2.2 Direct Estate

On Tuesday my car alarm went off. Pressed one of the buttons on the car key and the alarm stopped but went off again a few seconds later. Again pressed one of the buttons and it stopped and all seemed fine.

However the next few (10?) times when the ignition was switched on the message "Check Safeguard" came up but has now disappeared.

Diagnostic run tonight came up with the following:-
B2955-06 x10 anti-theft circuit low voltage/ open circuit
B2955-0F x10 anti-theft data link
B3916-0F x10 no comms with alarm siren
B3901-00 x10 wrong environment identifier received

Any suggestions on what I should check out would be warmly welcomed.

One thought is the handbook states that the alarm has its own battery. Would it be possible that this battery, at 7 years old, has reached the end of its life?

Many thanks Dave