Multiple warnings and car won't start (automatic gearbox)

Last Tues car was working fine. Left it on the drive for an hour and then when tried to start came up with multiple faults:
Brake system fault
Airbag fault
Anti pollution fault
Handbrake fault
Seatbelt fault
I think pretty much every fault going, however Windows would work, but car wouldn't lock either.
Tried to unplug battery and re-couple....this made it worse as absolutely nothing worked.
Want to try and sell at an auction as can not afford to spend loads on it but need to get it working first..
Any ideas/advice would be appreciated