Why won't my Mac shut down?

Episode 1651 (1:18:34)

Angela from Dartmouth, Nova Scotia, Canada
2015 iMac

Angela has a 2015 Mac and when she shuts it down, it turns back on. Leo says it's an incomplete shutdown, with some app hanging it up. A wipe and reinstall of the OS should make it go away. Make sure you backup your data first.

You can launch the activity monitor and it'll show you all the processes that are running.