Milwaukee M12 Soldering Iron: Troubleshooting and Repair with no special tools

How to diagnose and repair a Milwaukee M12 Cordless soldering iron that powers up but doesn’t heat up. These are great soldering irons but are not immune to abuse! Parts: -Thermal fuse: 5 Pcs NEC Microtemp Thermal Fuse 142C TF Cutoff 15A 250V SF139E https://www.amazon.com/dp/B0127L0PKO/... -Replacement heating element: American Hakko A1321 Heating Element For 907/908 Wa https://www.amazon.com/dp/B01GTLAXMI/...