Some 15 years ago I had a breadboard with CMOS 4000 logic chips connected to a power supply, left the room and came back later to see it dead. I saw some faint

Some 15 years ago I had a breadboard with CMOS 4000 logic chips connected to a power supply, left the room and came back later to see it dead. I saw some faint burn marks on the breadboard. I never figured out what caused this, but 99% it was my little brother swapping banana plugs to the supply. CMOS chips don't like that as ESD protection diodes are put in forward mode conducting a lot of current. Depending on power capacity of supply they may or may not survive.