Then throw the chest at the ammo box.

You pick up the chest, which feels somewhat empty, and hurl it at the crate. After being weakened from the kicks, it cracks a big hole in the chest. You can see the contents inside.
use the not-key as a miniature crowbar and pry open the weakest nail you can find on the ammo crate
The key-like tool seems to be fit for this job. It's probably also a better, less splintery and destructive way of opening it. You set the chest back into it's original place, out of the way.

After tedious nail-prying, the front of the crate comes off. You're not sure what you expected, because it's labeled as exactly what it contains. It's filled to the brim with small magazine boxes. There's also a paper-wrapped cardboard box in the top corner. It has a blank red tag.
examine every object
Does that wire have any significance? Is it attached to the ammo box somehow or is it just a plain wire?
You look into the crevice between the wall and crate. It seems to be connected to something outside of the room.
As for the rest of the room, there's an identical crate by the chest, but it's unmarked. The chest has a lock on it as well, and some numbers printed on to it. The entire room has a far-off rumbling sound, probably from a generator. There's not much else to the room you haven't seen already.
check inventory
You currently have the WEIRD TOOL and FOLDED PAPER. Hell, let's pocket the spare ROPE that was tied to your hands.