Verb go bad has 2 senses
- fail, go bad, give way, die, give out, conk out, go, break, break down - stop operating or functioning; "The engine finally went"; "The car died on the road"; "The bus we travelled in broke down on the way to town"; "The coffee maker broke"; "The engine failed on the way to town"; "her eyesight went after the accident"
--1 is one way to change
- spoil, go bad - become unfit for consumption or use; "the meat must be eaten before it spoils"
--2 is one way to decay