I got into a roll away accident with an electric truck double parked on a hill due to the truck's emergency brake failure. When I stepped out of the truck and ran across the street to do a pick-up, the trucked started to roll down the hill. When I got suspended, they did an investigation on the truck thru a third party. The third party truck investigator reports came back that emergency brakes was fine and the report said the emergency brakes is fine when the truck is parked on a hill. My manager also did a test of the emergency brakes and he said the brakes held up on a hill. Now my manager said that i should of turned my wheels, which I didn't know i was supposed to curb the wheels even if I double parked. This will be my 3rd warning letter and I don't want to lose my job because of the faulty truck caused the 3rd letter. Please help me on what should I do.