One thing (among many) I learned here is that you really dont have to heat the honey. Ive been just adding room temp water and honey since I came to Gotmead and things work very well. Maybe a little more stirring to mix, but you never have to wait for the must to cool or worry about killing the yeast via temp shock.
That said, what was the must temp when you pitched? If there was a big temp difference between must and starter, you might have a problem. If that isnt the case, Id just let it go for a while. Looking for airlock activity doesnt alway work out, you really should use a hydrometer to measure gravity change. Ive had a few leaky bung/airlocks that dont bubble, it happens.
For the temp, I have seen a few people here use creative methods for temp control, like ice baths (or cold water in the bathtub, cold wet towels wrapped around the carboy and a fan, etc. I would try to get the temp down to the 75 range, but if you cant the only effect it should have is a stronger alcohol taste in your finished mead. Aging will (might) take care of that.