Why can I not boot up my imac
Why can I not boot up my iMac
iMac 21.5″, macOS 11.2
You have not provided us with any useful details. So please read Writing an effective Apple Support Communities Question and look for the type of information we need to know about your system. Then please re-write your question.
You can also refer to https://support.apple.com/en-us/HT204156