do the seatbelts release manually or only if in accident

Seat belts are not suppose to release in an accident. Do you mean after they lock up for an impact? If so, they should release on their own, if they do not try playing with them, tug a few times on them and try to get they to retract.

The front motorized shoulder belts have an emergency manual release lever near the parking brake. It is only to be used if the shoulder belts have locked up after an accident. The lap belts release in the usual manner.