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Hi hoping someone can help. I have upgraded my 2010 iMAC 21’. Installed a new SSD and after trying to do internet recovery can get to the Disk Utility. Have erased the disks and reset to MAC OS Extended (Journaled) - GUID Partition Map When I try to reinstall macOS High Sierra, I can see the disk, it runs until about 2 minutes to go, and then reboots to the grey screen and the question mark. Anybody got any advice please? Thanks in advance.
Let’s give this a try: Restart your system and press the Option (⌥) key to get to the Startup Disk Manager. Then using the keypad arrow keys select the drive you installed the OS onto. Did that work? If it did go into your preferences and set the startup disk for the boot drive. Shutdown, Unplug the power cord for the night, in the morning plug your cord back in and restart did the setting hold? If not your PRAM battery needs replacing. Reference: Mac startup key combinations
