iMac shows "The disk is Locked",How do I reset it and access my iMac.
[Re-Titled By Moderator]
You cannot do anything with the OSX Base System, that s what is stored i Firmware.
Start up from macOS Recovery
Option-⌘-R
Upgrade to the latest macOS compatible with your Mac.
In Disk Utility>View, select Show all Devices, highlight the top left entry.
Run Disk First Aid on all items in the left panel, from top down.
APFS won't work for Sierra or earlier, Sierra or earlier needs MacOS Extended Journaled. High Sierra won't work for APFS on earlier Macs.
If all else fails...
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Use http:// instead of https://
https://www.youtube.com/watch?v=ouNQS36dIBw&t=95s
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