The laptop screen will not stay in the upright position. When you open the display at a 90-degree angle it will not stay in that position. The screen either falls back or forward.
One or both display hinges are broken.
Possible troubleshooting steps and repair solution:
Most likely one of the hinges or both hinges is broken. You have to disassemble the display panel and find out which hinge is broken. When you replace the broken hinge, do not forget to inspect the second one. If the second hinge feels loose, consider replacing it too.
If one of the hinges is broken try replacing it as soon as possible. Using the laptop with a broken hinge may cause the video cable or LCD screen damage.