[Baffler]

Also, the lights can flash to indicate a problem with the circuitry. The little stainless strip that operates the microswitch in the bonnet catch/latch can distort and is a usual suspect

Being 20 years young the siren batteries or PCB may have failed but before you go spending money on a new one you might want to carry out the following check:

With the bonnet raised, all other doors in the closed position, press the stainless strip with a pen or a screwdriver to deactivate the microswitch, place your ear close by as you press it in order to hear the microswitch, then try locking the car via the fob. If the indicators don't flash you've found the problem......now realease the strip to test the siren 😁