Hi @aria25 ,
It might be that the antenna cables have been damaged in the hinge area as this is where they pass through to the lid.
Here’s a link to the [https://topics-cdn.dell.com/pdf/inspiron-15-7559-laptop_service-manual_en-us.pdf|service manual] for your laptop, taken from this [https://www.dell.com/support/home/us/en/04/product-support/product/inspiron-15-7559-laptop/manuals|webpage]
Scroll to p.80 to view the necessary pre-requisite steps and then the procedure to remove/replace the display assembly. This will allow you to replace the antenna cables.
Here’s a link to just one [https://www.ebay.com/p/WiFi-Wire-Antenna-Cable-for-Dell-Inspiron-15p-7000-5577-5576-7557-7559-Laptop/27025428034|supplier] of the part. It is shown just to give you an idea of the cost of the part. There are other suppliers online that may suit you better. Just search for ''Dell Inspiron 7559 WiFi antenna'' to get results for suppliers of the part.