Restart the system and press the ***Option*** key to get to the Startup Manager so you can select the original drive. Once it has started you will need to go into the Startup Drive preference setting.
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Restart the system and press the ***Option*** key to get to the Startup Manager so you can select the original drive. Once it has started you will need to go into the Startup Drive preference setting resetting it let it reboot to make sure it’s set.
Ah! Likely a simple problem!
Restart the system and press the ***Option*** key to get to the Startup Manager so you can select the original drive. Once it has started you will need to go into the Startup Drive preference setting.
Reference [https://support.apple.com/en-us/HT201255|Mac startup key combinations]