I constantly debugged/undebugged my yellow V3 to the point that the sound wires quit working. I want to get them soldered back on because it was my first Tamagotchi.
Once, I accidentally dropped my Ruby Red V5 in coca-cola!!! I dried it out for a few months (i was a very paranoid child scared of electrocution) and surprisingly enough, when I put a new battery in it worked! I actually have it next to me right now. The Tamagotchi certainly looks battered, and I regret the negative treatment it has gotten but hey, I can't turn back time.
My P's both recieved a lot of battering because I was frustrated with the buttons. Since then I've tried to never ever take out my frustration on my electronics except for the ones I don't care about.
There was also the time I accidentally got hand sanitizer on my V5 melody pattern. It made the very bottom of the screen permanently fog up, so now it's difficult to see whether it needs attention or not.
When I got my first Tamagotchi, I raised her without caring about the hungry and happy hearts. I thought that the outlined hearts had to disappear for the Tama to need food or to play games. Harley died because of my ignorance. I've also let multiple Tamagotchis die on me or reset them myself because I lost the time to take care of them.