That is frustrating, and it is usually a quick fix: on most Wacky Robots that will not work, either the LED or the battery is the wrong way round.
Check the LED first. Its longer leg is positive (+) and its shorter leg is negative (-), and they have to match the symbols marked on the circuit board. If they are reversed, ease the LED out, turn it round and push it back in.
Then check the battery. It should sit the right way up in the holder, flat against both contacts.
If that does not solve it, message us here, or email [email protected], with your order number and a photo of the assembled robot, and we will work out what is going on. If a part turns out to be faulty, the replacement is free.
