The following may be helpful to you.
https://drive.google.com/drive/folde...XdidFJ6SHRPVzg
I am assuming that the thermal fuses you are replacing are the ones on the blower.
When you set it to air only do you get just air?
Also when you set to different temperature does it actually change the temperature?
If not then it is probably the control board, either the heater relay contacts are welded together or the electronics that control the relay are shot (holding it on all the time).
You may want to recheck your vent system.
Vents running through the roof are a pain.
If you are just using a snake to clean it then often you just loosen some of the lint plug. Then when you turn the dryer on it pushes more lint up plugging the vent on the roof.