All because of what seems to be a broken internal clock, the Dell Studio 1535 laptop will automatically boot into diagnostics mode around 50% of the time and there’s no way to prevent this.
Thing is, at least Linux Mint will always give you the correct time right after logging in if you have a network connection and network time is enabled, so this feels like much ado about nothing on the laptop’s part and basically makes the laptop unusable otherwise.
(and it’s not the battery - I’ve tried replacing it with no change in result. Also, a dead battery wouldn’t explain why it would sometimes claim a date in the future by many years, like 2074, when booting)