Please try to put another ground minus - cable between battery and engine, just connect the battery minus pole with any part of engine or open car skelet and try to start, if it starts then check the ground (minus) wire from the battery to the transmission! I had the same issue with AT-124 error cod...

I think its one of a relays (try to move it or replug) right above the cooler fan, behind the Volvo mask (am I right?)
I also had no start issiue after driving thru a snow mess.. and injection relay replug was the solution