So, an error I have to point out... those little stickers that say "Warranty Void if Removed" were deemed to be unenforceable in the US back in the 80's. The 1975 Magnuson-Moss Warranty Act ruled that a company cannot simply state that because a customer opened a device that they broke it, the company must be able to prove how they broke it. The FTC has created guidelines for companies to follow under this Act. In point of fact, this act made simply placing these stickers onto devices to be illegal, and yes... these companies pay fines to the FTC for these violations, constantly.
Also, if the device is "old" as your friend/sister states then it wouldn't be under warranty anyways. Most computers come with a 1 year or shorter warranty.
And yes...within the wording of the warranty it usually had wording that makes it void if you make any alterations, however this is also not allowed under FTC guidelines and the company must prove how you broke it.
And finally.. yes the FTC is only in the US... in the EU a manufacturer must provide free repair or replacement of a defective product without limitation for a period of at least 2 years, if they cannot then they must offer a refund. Further, if they declare that you voided the warranty you can force them to refund you under the Sale of Goods Act.
My biggest point, your game may be set in a fictional land and not in the US, but it looks like the US, and any independent tech support, such as at your local college, would know that the sticker is illegal and unenforceable.
*Edit to add... a non-chargeable battery does NOT brick a computer, it simply turns a laptop into a desktop.
*2nd Edit... in the US it is illegal to handcuff a mute person. Like, it is so illegal that no matter what crime they committed they just got off free. That is because of the freedom of speech, a freedom which cannot be taken away until AFTER a judge has ruled and found you guilty. And by handcuffing a mute person, or a deaf person, you are taking away their freedom of speech unconstitutionally.