You could heat them in the oven or fry them in oil; but yeah, I think most people just zap’n’scarf.
It seems like half the time I buy the Patio burritos the beans aren’t cooked all the way through. Refried beans shouldn’t be crunchy. Even when the beans are cooked right I think they’re a long way away from ‘good’ but I guess as frozen burritos go they’re serviceable. To be honest I don’t really like any frozen burritos but if I’m hungry and have hot sauce they’ll do in a pinch.