Destroyed the "warranty void' sticker is not an indication of service or alternation work being performed.
There are many ways you can invalidate your warranty that have nothing to do with unauthorized service. Fact is that the manufacturer doesn't
have to allow you access if they provide free warranty service. Now, with that aside, they can set all sorts of criteria for maintaining your warranty. You usually can't deface the serial number. Sometimes selling the item voids the warranty. Removing the warranty void sticker voids the warranty. Ferinstance, here's the Xbox fine print. This is typical of any consumer product, and I guarantee you that lawyers have scrutinized this many times over:
5. Warranty Exclusions
Microsoft is not responsible and this warranty does not apply if Your Xbox One or Accessory is:
(a) damaged by use with products not sold or licensed by Microsoft (including, for example, games and accessories not manufactured or licensed by Microsoft, and “pirated” games, etc.);
(b) used for commercial purposes (including, for example, rental, pay-per-play, etc.);
(c) opened, modified, or tampered with (including, for example, any attempt to defeat any Xbox One or Accessory technical limitation, security, or anti-piracy mechanism, etc.), or its serial number is altered or removed;
(d) damaged by any external cause (including, for example, by being dropped, used with inadequate ventilation, etc., or failure to follow instructions in the instruction manual for the Xbox One or Accessory);
(e) scratched, dented, etc. or shows other cosmetic damage; or
(f) repaired by anyone other than Microsoft.