Okay, though building the jammer - really a focused pulse device, since building a more sophisticated devices would need several hail-mary rolls to succeed, is not something to be accomplished under flashlight, especially since you are not modifying a similarly functional device. Something as simple (!) as a cell phone, walkie talkie or even the magnatron from a microwave oven would do nicely.
The Doors have no visible hinges, and did not automatically open at your approach. Best guess from the structure of the doors are that they might slide to the side.