Hi @jaymcpherson
It's a shame that you can't connect an external monitor (TV?) to check that it is either the screen or a motherboard problem
More than likely a dark spot in only one area of the screen, is a screen LED backlight problem so the LCD panel will have to be replaced.
Here's the [http://h10032.www1.hp.com/ctg/Manual/c04511833.pdf|maintenance and service guide] taken from this HP support [https://support.hp.com/nz-en/product/setup-user-guides/hp-pavilion-15-notebook-pc-series/model/7668724|webpage] for the laptop.
Go to p.55 to view the procedure to remove/replace the LCD panel.
On p.30 Item #3 you'll find the HP part number for all of the 15.6" LCD panel types that can be used in the model. Usually the part number can be found on the back of the LCD panel somewhere if you wish to verify which type is installed.
Search online for the part number appropriate to your particular model variant, to find suppliers that suit you best.