The Tunnel is so dark and your bat signals don't work.

There is a light source next to the Tunnel that you could somehow use.

Hmm.. that is true. Maybe you could mirror it?

There is a mirror next to the tunnel. Grab it and hang it on the hanging skeleton.

The mirror is little dirty. Maybe you could clean the mirror?

So, the mirror is hanging with the skeleton. What else could be wrong?

Is the light red? You know red light doesn't help. Take the red light away.

Shut the light down with the Lever in the Upper Level and remove it then. Replace it with the Halogen Lamp and light it up.

Is the mirror hanging high enough? You should get it up.

Oh yeah, the lights are in wrong phase. If the light is on, the signal is down, and vice versa. Could you fix the signal to inverted position?

Fix it by putting the Bi-Nausal Power Inverter into the signal fuse box.