I once killed a kitten and then brought it back from the dead with CPR.

It was a stray that showed up, was covered in fleas. I decided to bathe it and it didnt occur to me that cold/room temp water would not be good for it. It was fighting but I just assumed it didnt like the water. Then it just went limp.

Quickly googled CPR cat, saw something in the (pre-AI) preview thing about blow into its nostrils (the chest was quite surprisingly inflating like a balloon without much force), and just started doing that while poking/pinching its heart area. Some amount of time later - could have been 5 seconds or 45 - it sputtered back to life.

I found it a foster shortly after. I have significant allergies to cat hair, scratches etc...