I opened the screen but can't see the battery inside?

Hi Thomas! I moved your post from a comment to a question to get you more help!

I think what's happened is that the plastic frame separated from the display, so that the glass came up, but the metal clips and LCD plate (you're seeing the backside of the big metal plate in the third photo) stayed in the phone. You can see in this step that the glass can sometimes lift away from the frame.

You'll need some thin prying tools, like a plastic opening tool or opening pick (preferably plastic, not metal tools). Insert the tools between the plastic edge and the metal of the case, use step 3 as a guide for where to pry. Once the frame is out of the phone, you should be able to follow the rest of the guide!

It might be smart to post a photo here before you start on this, in case I'm wrong!