Meanwhile (cue creepy music) the whatever-it-is has done whatever-it-does. The lid is off and the brick is on the ground. To the crumbles. So this time I placed two bricks on the lid. Lights didn't phase whatever-it-is, but apparently rain did. So it's not currently living IN the barn. Just nearby. I should pay much more attention to times when the birds, esp. the crows, go nuts as an indication that whatever-it-is is out and about. They were silent this morning, but I did hear some activity in the past 3 hours after the rain stopped.
Will whatever-it-is be stronger than 2 bricks? Brighter than 2 bricks and some humans? Tune in tomorrow and find out.