How do I solve the puzzle behind the wall panel?

Three colored areas of rotating tiles. Each color needs to form a closed circuit. Easy.

Only the moment you complete one circuit, a panel slides over them, allowing you to access only very specific tiles.

Rotate the visible piece of the active circuit to get the panel to open again.

Make sure to remember which tiles are accessible through the panel. It's the ones connecting the circuit to the line leading out of the board.

Complete all three circuits apart from these tiles. Now rotate one to get the panel to close.

You have now access to the two remaining unconnected tiles through the panel. Rotate them till they light up and you're done.