car will not always start

[stag]

my 97 cerbera 4.2 is having problems starting.
Car starts on the button when cold, but when hot does not send a feed to the starter motor at all.
a new starter motor, has been fitted, new starter switch, new relay. Even tvr are foxed. could it be alarm system which is standard with car.

any advice would be welcomed.

many thanks

[porscher]

alarm system is at fault

[FourWheelDrift]

Immobiliser