if the starter solenoid clicks out then it's likely the battery. but if all the electrics are working normally but no starter action I'd say you have an immobiliser fault. a standard immobiliser only stops the crank circuit normally, allowing everything to work including the fuel pump, whereas an aftermarket immobiliser has the option to also stop the electrical circuits working, which acts as a double protection, or failsafe. Try a jump start, if not, then either a fuse or a relay is away, or at worst the immobiliser isn't deactivating. used to fix that sort of thing all the time when I fitted alarms and immobilisers.