Got a new mower today! Get to return it tomorrow!

It's a Ryobi battery powered 20in mower. Charged the battery fully but the damn thing cuts off after 10-30 seconds of running no matter what. Just holding it in place with no load on it and the deck height at max, it'll just stop for no reason. Assuming that there is a short in it somewhere. Not feeling confident about an exchange for the same model.