Those "Warranty Void If Removed" stickers are actually illegal. Under the law, the manufacturer cannot void your warranty because you opened up something you own. If you open it up and break something in the process, they can refuse to cover what you broke, but that's because you broke it - it wasn't a manufacturing defect.
Say, for example, you have a Nintendo Switch, and one of the buttons stops working. You decide that, before you go through the trouble of sending it in for repair, you want to try opening it up and cleaning the contacts. Nintendo can't refuse to fix it unless they can demonstrate you broke something in your repair attempt.
Companies can't even legally void your warranty for using 3rd-party parts, unless they can demonstrate damage caused by those parts. If you drop your Switch and break the screen, and fix it with a 3rd-party replacement screen, Nintendo still can't refuse to fix your flaky button from the example above.
Back in 2018, the Federal Trade Commission started cracking down on companies doing the "Warranty Void if Removed" stickers.
https://www.npr.org/sections/t...