Someone must have used the fireplace before you and left the vent open. Ugh. I have glass doors in front of mine that close. They have never been opened. Poor you and poor bees! I guess they were swarming into your apartment. Usually when they swarm you can call a beekeeper to come get them out of the bush or whatever they are in, but IN YOUR APARTMENT? No bueno, bees.

Apparently there is some kind of battery on the motherboard that can fritz out and cause problems, maybe he checked that one? I also have limited computer hardware knowledge.