See if there is a model number posted inside the storage compartment above the main door. Most likely your compactor was made by Whirlpool, but could also be Broan. Post the model number and I'll get you breakdown diagrams for it.

Typically, when a compactor is jammed and the door cannot be opened, you'd have to pull it out of the cabinet, unplug the power cord and disassemble from either top or back, depending on the brand. If it's Whirlpool, remove the top panel, then power nuts, then the ram - from there you can remove the door and whatever foreign objects that caused the jam.

Hope this helps.