Replace brake light bulb?

Hi my friend has just replaced my brake light bulb for me on my ford
streetka and in the process he's knocked the secure metal box down from its fixture that holds the car alarm and he can't get it to go back cos he needs a form of star Alan key that has a hole in it ????? Not sure if I've explained that for anyone to understand but we don't know where to get the part to fix it back on as its a form of security. Any advise would be much appreciated thank you in advance