Seat Ibiza Dashboard lit up with faults

Hi
I was driving when a number of engine warning lights came on, ABS, steering wheel, air bag, engine management light, electronic stability programme, locks starting locking and unlocking. It then started beeping x3 and rev counter drops. This all happened at the same time without warning. Has been serviced in the last month with no issues. Garage struggling to work out the cause. They have changed the battery and think it might be water in electrics?
I managed to drive it home but power steering also felt heavy. Help please.