Denon DCM-280 Drawer Won't Open

Disconnect the unit from the wall and open the case. You may find an exposed gear wheel or some means of manually operating the drawer.

So long as the power is off you should be able to get the drawer open without damage.

Then investigate whether a belt has snapped. Or whether it's a trip switch that's not operating.

Generally I then further investigate faults with the power on and so long as you keep your fingers out of the power supply area (usually around the transformer and the entry point from the wall mains) you should be okay.

If in doubt, find a repair guy who'll fix it for less than the price of a new deck -- these days not easy.