Roller shutter stuck midway.

Hello all, I am new to the forum and thank you in anticipation of any assistance. I have a roller shutter on my patio windows, which I appreciate is not a garage door but assume the workings are similar. The shutter is stuck midway and will not open or close. Just before it stuck I was experiencing when opening the shutter a drop of about several inches when releasing the up switch. The up and down switches do not operate and there is a humming come from the motor. I suspect it may be the condenser in the motor but cannot access the motor as the shutter obstructs access. The access cover is within the property. My question is how can you close the shutter fully as there is no manual override evident. Thanks in anticipation.