Disconnecting a Beeping Smoke Detector Above the Drop Ceiling?

I have read several threads discussing this topic and I understand the need to maintain home safety. However, my problem adds a new twist. I had a room added in the back of my lower level and the contractor put in a dropped plaster ceiling and covered up one of the smoke detectors.

The battery died and we can not access the detector to change the battery. I intend to place another detector in the vicinity of the nonaccessible detector, but need to somehow deactivate the one detector to stop the beeping without interfering with the operation of the remaining detectors. Can someone offer a solution?

By Rich from Vandalia, MI