system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How old TVs are getting fixed after you slapped it?
gpt
What you're referring to is called "percussive maintenance".  It's an age old technique that mainly works on older, analog equipment and appliances, but still has its uses with some newer technology.  

Sometimes an electrical connection gets a little loose or the contact points become corroded due to age and the environment.  A good whack on the side can often times jolt that bad connection back into place and allow the offending equipment to work again, at least temporarily.