Hacking Top screen isn't solid

[GWizard]

I have a problem,
When I shake my DS the top screen moves and I feel like it isn't solid.
Unlike mine, I tried my cousin's Onyx/black ds and it's very solid.

What can I do to fix this?

 

[Steevsee]

Your screen may have simply come loose as they are only held in the frame by some double sided tape. You will probably have to take apart the top section of your ds and it should just press (Gently!)back onto the sticky surface. There are several good guides online to help and it should be relatively simple.