I ended up using super glue to glue the crack together until I could get to the rv store. Then I put the TPO patch kit on top (super sticky stuff) and then went around all of the edges with a clear caulk that the rv store said is used with the TPO. I check my roof pretty often so I will just keep an eye on it. I didn't want to replace the vent because the plastic doesn't seem that strong and because of the location of the vent on the roof it might get hit by a low branch again. The TPO patch is strong stuff so I basically strengthened that area of the vent to be able to take more of a hit.
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