Did the boat turn over whilst coming off the trailer i.e. stern toward the sea, so could broach side on and roll or, did it turn over no where near the sea whilst still on the sand?
You do see some daft goings on slips and beach launches involving a degree of showing off. I have had requests from people to launch by freeing all attachments then reversing at moderate speed and hitting the brakes. Trouble is you dont know if it's going to break loose before the intended launch point.
The requests are always politely declined.
New boat is here, very happy!