First of all raise your Z height up a little. Around 60-80mm is probably fine. This allows clearance for the hotend assembly to be removed.
I reccomend removing the nozzle before you start removing the screws as its easier now.
Undo the 4 screws and two knobs on the front and the assembly will drop out of the cage. I recommend leaving one loose till last and then holding the hotend while unscrewing it as to not drop the assembly.
The the assembly removed. Unplug the extruder motor. Its this white plug.
Stand the assembly on end and remove the two screws the hold the fan in place. Then simply move the fan out of the way. No need to unplug it.
Below the hotend remove these two screws that keep the extruder stepper motor in place.
When those two screws are removed, you can pop the extruder back from the black plate and slide it out of the way.
For the extruder not working , you may check if the feeding gear is loose .
Then you may add the platsic sheet between spring and solider .It will give spring force .
Lastly, we need to loose this big screws .
Here is a link for reference .