No doubt influenced by Supreme Court to rule in landmark Patent Exhaustion case which held that once a product is sold, the manufacturer cannot require you to use a product in a specific way, as well as the Right To Repair movement. The thing is, there is nothing in the law which prohibits manufacturers from releasing required "updates" to a product which then causes those third party repairs to stop functioning. See also Apple iOS 11.3 update breaks iPhone 8 devices with 3rd party screens | Daily Mail Online
Those little "Void if Broken" stickers were very effective for me. Many times I wanted to take apart a electronic component and saw the stickers on the screws or slots and convinced me not to go further. I was afraid my Warranty would be cancelled and didn't want to take a chance.
They can deny if they can prove you broke it, but they have to prove you broke it and they are not going to do that. I was a service tech for a long time and can tell you those stickers are not enforced. They are just there to keep people out that have no business being there. In the USA manufactured items with warranties are covered by an Act originally for automobiles but has been upheld many time since it's inception to apply to any manufactured consumer good. Usually if you get a company that is being defiant just let them know you are going to sue them in small claims court and ask them if the air line ticket and lawyer fees are worth their time to try and fight it? Unless it is a very expensive item. They will work with you once they know you are not going away.
The Magnuson-Moss Warranty Act is a United States federal law. Enacted in 1975, the federal statute governs warranties on consumer products. The law does not require any product to have a warranty, but if it does have a warranty, the warranty must comply with this law. The law was created to fix problems as a result of manufacturers using disclaimers on warranties in an unfair or misleading manner. More at Wikipedia
Long title:An Act to provide disclosure standards for written consumer product warranties against defect or malfunction, to define Federal content standards for such warranties, to amend the Federal Trade Commission Act in order to improve its consumer protection activities, An Act to provide minimum disclosure standards for written consumer product warranties, to define minimum Federal content standards for such warranties, to amend the Federal Trade Commission Act in order to improve its consumer protection activities, and for other purposes.
Nicknames:Consumer Product Warranty and Federal Trade Commission Improvement Act
Enacted by:the 93rd United States Congress