So sorry to hear of your sad loss. My little Hermanns is 16mths old and I have had her for about 2 months. Even after that short time I would be lost without her.
And it’s common practice to open the door quite often so there’s a change of air, and possibly to check temps or the torts themselves...Refrigerator hibernation/brumation is quite common. Respiration is very slow when a tortoise is brumating, and the air in the fridge is enough to keep him alive through the winter.