In the infamous Andes F27 'cannibal' crash, survivors trekked several miles to the next mountain top where the tail wreckage lay, to salvage the batteries and try and get a radio going. They would then be able to call for help. Unfortunately none of the survivors had any idea how to wire the radio up. What they missed when they were collecting the batteries was the Emergency Locator Transmitter in the cabin ceiling of the tail section. They only needed to piss on the salt water battery pack to get it working and it would have attracted the search teams to the site.
I assume that your survivors will be clever enough to get the APU running, fire up one of the galleys, hook up the electrics for lights, jury rig the In Flight Entertainment system for movies and music etc. but too dumb to get the emergency locator beacons working... ?