Compactors often fail with the ram in the down position; it cannot be opened. Of course the trash soon begins to stink. Repair requires removal from the cabinet and disassembly. Any of the limit switches mentioned under "My compactor is Dead" can cause this situation; check them first.
However, a worn out ram system including worm gears, chains or a worn out motor can also be the cause. Careful inspection will quickly reveal any damage. Many compactors use two rotating worm gears with the nuts that are attached to ram. Others use a ram system very similar to a scissors jack. We have opted in a few cases to load a bad compactor in to a van and repair it at home. They are easy to remove and not very heavy. This allowed us to thoroughly check out the unit before returning it to the customer.
Worm Gear Nuts
Broan Chain Design
Plastic Drive Gears
Compactor Motor
Scissors Design