iMac 2009 with High Sierra.I was in recover mode and Terminal and enabled sip. Got the message to restart so went to apple logo and restarted. I didn't select a startup disk beforehand and now progress bar won't finish. It stays frozen with apple and bar.
Power off & try holding Option key at startup, does the boot choice screen show up?
Very likely a hardware failure, please remember the computer is woefully obsolete and should have been replaced years ago.
Please replace with a current Mac, you can use Setup Assistant to restore your data from your Time Machine backup.
Sorry I know this is not what you wanted to read however imho it’s the right way to go.
Best of luck.
imac progress bar won't finish
