The Right to Repair is a movement that intends to restore product ownership to consumers.
In the 20th century, many electronics and appliances came with repair manuals; and for anyone who requested it, schematics were also available to understand how the components on a circuit interact in order to do low-level repairs.
Today, finding repair manuals that come with a product or are available is something that has become increasingly slim. On top of that, obtaining schematics have become near impossible due to non-disclosure agreements and copyright laws.
Consequentially, manufacturers that make devices have the final say in whether or not a device can be repaired, who can repair them, and how much a repair costs -- no matter what is actually wrong with it.
It's not just repair, though. This also extends to how you use the device, even though you "own" it.
More information on the movement:
https://www.ifixit.com/Right-to-Repair
https://www.nytimes.com/wirecutter/blog/what-is-right-to-repair/
Adam Ruins Everything - Why You Don't Own Your Tech (Youtube, on right)
What Is Right To Repair - MKBHD (Youtube)
Apple Store vs. Repair Shop: What the Right to Repair Is All About | WSJ
Repair Your Own Devices:
iFixit: The Free Repair Manual (https://www.ifixit.com/)
Replacement Parts (https://www.repairclinic.com/) (also check with the maker of your device and eBay among other sources)
Adam Ruins Everything - Why You Don't Own Your Tech (YouTube)