Chevrolet Lacetti chevrolet lacetti 4 pin main relay fault

The car won't crank and nothing works it's had a new battery very recently, I've had a problem with the clock spring which I had to replace due to the airbag light staying on and the battery was disconnected for 24 hours. Upon reconnecting it this problem has now arisen with the relays clicking rapidly in the fuse box from the engine. I identified the main relay by touching it which was clicking loudly and from the relay diagram under the fuse box cover and then swapped it for a know good relay and the car jumped into life but a few hours later the same problem has come back. I've tested the main relay for resistance and continuity and applied power to it and it clicks and checks out ok. I can't see any burn marks to the fuse box where the pins connect and don't have a wiring diagram, it's as though the car has a dead battery but voltage for the battery is fine but the dash lights are low as well. I presume there's some type of wiring problem but don't know where to begin??