HOLD ON THERE........
Before you start ripping things apart give the original glue job some time. Unless you were drastically short of the amount of catalyst (hardener) the epoxy will reach a full cure with intended strength. If your mix from the night before was still tacky, look at it in another day or two. Even with a significant lack of hardener, the epoxy will reach full cure...just takes more time. Also, those joined surfaces you can't see are not as soft/tacky as the stuff in your mix pan.
Heat may speed cure but it would take low/long exposure to help. The safest way to use heat would be something like putting the assembly inside a closed up car in the sun on a hot day. Generally, the epoxy will start to lose strength at close to 300 degrees and by 350 it's history.
Jim