Found an interesting idea while Googling and it said to remove the Positive battery connector (be very careful not to short anything out while doing that) for a minute and then put it back on (again being very careful not to short anything out). This had something to do with a capacitor. No cost to try, but just remember that it is very easy to short your wrench to something while doing it and causing more problems. If you try this, make sure you have your radio code, etc.
Another safer way to do it is to disconnect both battery connectors and hold them (the connectors with vise grips or similar) together for around a minute to discharge any 'black' voltage (basically discharges all the capacitors) and then reconnect them. Remember to always to remove the Neg battery connector first and always replace it last.