"Voiding" a warranty is an irreversible action -- once it's voided, it cannot be reversed. Kind of like how you can't "un-void" a voided check.
Maybe we're using different terminology to describe the same thing... Apple will, in many cases, not
honor a warranty repair if enough modification has been done to the machine that they're no longer comfortable working on the machine.
I've had plenty of experience with repair depots to know that swapping out the RAM, hard drive, and/or video card (in the case of Apple towers) will typically not raise any flags by the tech, but then again, in Apple's retail stores, they seem to be more stringent with their policy. Enough barking up the right tree will, in fact, get you a warranty repair on a Mac mini that has had both the hard drive (be it an SSD or platter-based hard drive) and RAM upgraded.
I was just stating a fact that exists by law in the United States (that a manufacturer cannot void the warranty on, say, the RAM or motherboard if the user upgraded, say, the hard drive, unless damage was done to those modules in the upgrade process), not trying to express my experience with repair depots or start an argument.
Apple has never said nor stated anywhere on their website that upgrading the hard drive or RAM in either a Mac mini or Apple-branded laptop (two computers that may or may not be harder to upgrade those components in) will void the warranty on the rest of the computer.
I'm not going to go through specifics, but I know what I'm doing.
You don't have much experience with the repair depots, do you?
Neither fryke nor I are questioning your repair abilities or knowledge about Mac computers. No need to get defensive.