To add to @jayeff ‘s very helpful answer: I think the piece of metal Lauren is referring to might be the hinge connecting to the metal backplate. This might have come loose because it is only kept together by glue, which looses it’s strength after a while. It is a quite common problem for the Lenovo Yoga 500, 700, 900’s etc.
A possible solution is to glue it back together using a strong epoxy, this however requires you to take off the screen itself. For further instructions please see WiredDan’s very helpful posts on Lenovo’s forum:
Post explaining the problem: [link|https://forums.lenovo.com/t5/Lenovo-Yoga-Series-Notebooks/Yoga-710-Screen-separating-in-bottom-right-hand-corner/m-p/4042656?page=1#4131270|link].[br]
Post providing a solution: [link|https://forums.lenovo.com/t5/Lenovo-Yoga-Series-Notebooks/Lenovo-Yoga-700-710-720-900-broken-hinge-cracked-screen-glass/m-p/4264992#M69807|link].