https://www.npr.org/sections/thetwo-way/2018/04/11/601582169/warranty-void-if-removed-as-it-turns-out-feds-say-those-warnings-are-illegal

Oh, you've seen them before: those little stickers or tags making clear that if you want your warranty on a product to remain valid, you'd better leave one or more of its parts untouched. The idea, of course, is that consumers are barred from using third-party parts and repair services for the product if they would like to hang on to that guarantee.

Well, as you've probably long suspected — or desperately wished, at least — those warnings are bunk. Worse than that, actually: The Federal Trade Commission says they're illegal.