OK, solder looks better. I notice the transistor looks like it got pretty hot when you were soldering the tab, not sure if that is just flux or if the transistor kinda melted a bit? (prob just flux) Not impossible that you over heated the MOSFET during soldering, but not the most likely scenario either....
Speaking of most likely scenarios... Are you sure you are using the proper wires from the CAT5 cable? There is +5V in the CAT5 jack to power the servo right next to the BLOW pin, if you were to connected the +5v wire to the blower by mistake it might spin at a slow speed.... Verify by continuity you are using the right wires...
If you have verified you are using the right wires, then next I would go in the HM Config and change the blower from VOLTAGE mode to PULSE mode. In Pulse mode it doesn't use the feedback circuit, so if it works in Pulse mode check what's going on with the feedback circuit.