yes disconnect for 5 mins or so and re connect. if this dosnt work you can disconnect the siren so as not have neighbors complaining while you sort it. Drive into Halfords for a battery check as well, but I dont personally think this will be the problem as you are getting it having just driven home when battery will be well charged up. Also make sure boot and bonnet closed properly. Allso check micro switch in fuel flap not sticking (wd40)