My daughter was at university and finished for the day, packed her coffee thermos cup into her rucksack with her MacBook Pro... By the time she got home, the MBP had a lovely moiré pattern on the screen, even though it was turned off!
The sugary coffee got into everything, including the hard drive! It taught her a valuable lesson about keeping backups (I hat given her USB sticks and a OneDrive subscription, but her Dissertation was only on the hard drive)! Luckily, her grandfather was generous and bought her a new (at the time, 2017 model) and she got me to set up Carbonite on it, before she even started working on v2. of her disseration.