Hi @timmer96 ,
You may have to remove the base cover and check what the problem is.
The back cover screws into the palmrest assembly (top cover housing the keyboard etc).
To get to the palmrest assembly, the laptop has to be completely dis-assembled
Here’s a link to the ifixit Dell XPS 15 9550 Back/Underside Panel Replacement guide
Here’s a link to the service manual for the laptop, taken from this webpage and which may be of some help if you need to get to the palmrest assembly. Scroll to p.87 to view the necessary pre-requisite steps to get to the assembly.
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