The bulb is fully installed and the connection is complete, as near as I can tell.
Popping the trunk without the key in causes the board to output ~10% light, significantly less than the stock bulb. When they key is in, it's light broad daylight in the trunk.
This is the same case for the vanity mirrors and the glovebox, though I pretty rarely use those without the key in, so they don't bother me.
It strikes me as some sort of dirty ground issue, but I can't imagine how turning the key changes that without actually starting the car. If I swap the stock bulbs back, they work at full brightness.