Probably the squirrels again.
sounds like u bought a bad'in mate...
Try locking the car with the remote , leave it a minute or two then open the car door with the key . This " should " set the alarm off . If it does then you know it's working .
skuttle panel ?
if its the standard key fob, its a renault alarm.
A multimeter will tell you if the siren's knackered. Get a replacement from a scrappy, loads of them around.