my very first self-build when I was like 15 or something, AMD CPU installed but upon trying to squeeze the cooler onto it the clips on the boards plastic seating broke (its still insane how much force this needs) and my father tried to fix it with fixating the cooler using copper wire but ofc the pressure was not enough so upon boot the CPU just burned immediately.
I was devastated but got both parts replaced and learned a pricey lesson that day.