Can a repo man break an automatic garage door opener to repossess car?

No, a repo man generally cannot break an automatic garage door opener to repossess a car. Doing so would likely constitute property damage and be illegal. Repossession laws vary by state, but they generally require the repo agent to act lawfully and avoid causing unnecessary damage. If the car is in a garage, they'd likely need to gain access through other legal means, or perhaps not repossess the vehicle at all if access is impossible without causing damage.