Talk to Lightkeeper — receive the Armored case

Lightkeeper now hands you the Armored case — the same case Prapor's men died trying to recover. It goes into your inventory's special slot, which is the dedicated row at the bottom for quest containers. Empty that slot before clicking accept — if it's occupied (e.g. by another quest item) the trade silently fails and you'll have to repeat the dialogue.

The case itself is locked. The next step is figuring out how to open it without bricking what's inside, which is where Mechanic and the experimental signal jammer come in. From here on, every step funnels toward the keycard hidden in the case.