"Scam on Mac Book start up?: [...]the screen switches to what appears to be the Apple start up screen with white progress bar and logo, but never boots up, instead pop up message appears: ‘A critical software update is required for your Mac, but am error was encountered while: installing this update. Your Mac can’t be used until this update is installed.’ Is this legit?"
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Troubleshooting a Mac Stuck in a Boot Loop:
Yes. This is legit. Your Mac is stuck in a boot loop. This typically occurs when you go about installing an update, and it stalls while in the process. So, see if the following works.
I. Boot in Safe Mode:
In Safe Mode, Login Items do not run at login, certain preferences are set aside, and damaged system files are then reset. So, once booted in to Safe Mode, wait 30 seconds, and then boot up normally, attempting another update install. For instructions, go here: How to Use Safe Mode on your Mac - Apple Support
II. Reset your SMC and your NVRAM:
(Applies to Intel-Basel Macs Only) Sometimes changes (i.e. Installations) are made to the system and then settings (i.e. Networking) become corrupted, technically. So, reset both on your Mac. So, reset the SMC and reset the NVRAM or PRAM. It might take three tries. to fix this. So, be certain you have the time to do so.
Start With This:
III. Re-Mount the Drive:
Boot into Recovery Mode (Intel or Silicon) . You need to click the “Mount’ button to proceed. So, select the drives, and then click "Mount" Try rebooting once more. If of no success, then click unmount button, and then the mount button. Try rebooting once more. It looks dulled-out. So, if you cannot click it, then click the First Aid button to fix this volume.
