Following a recent house fire we're advised by the Fire brigade to get a new router as the smoke might have damaged it internally? It wasn't burned, but was in the same room and being on would have been circulating the air and smoke in the room.
There's no cooling fan in the router so it wouldn't suck smoke in. It depends on how much smoke and how hot it got. If there's no damage to the power supply and cable I'd try it, it will either work or not. If you're not happy testing it yourself, take it to someone who knows what their doing to look at.