What Does the Switch in 'The Construction Site' Do?

Question

I almost missed it, but this box is one of the switches like you see in the first tutorial level. I hit it with my bionic arm, and there was a satisfying clunk, but I have no idea what it did. Did it change something waaaay back down at the bottom of the level?

Answer 1

It opens this door:

Inside you can get

the Secret Challenge Room 5