How to exit Internet recovery loop and reinstall macOS on a 2018 Mac mini?

Keep in mind your Mac must be connected to the Internet for the system to verify everything is Ok in order for the system to properly authenticate you and confirm the OS & system are Ok.

I wonder if a firmware password lock has been enabled. Try holding down the Option key immediately after hearing the startup chime to see if you are presented with the Apple boot picker menu or a padlock icon.

Try an SMC Reset (follow the instructions for a T2 Mac) and a PRAM Reset (try holding it for two chimes if possible, but many T2 Macs will only allow one chime).

Otherwise it sounds like you will need to perform a DFU Firmware Revive, or more likely a DFU Firmware Restore where the latter will also reset the internal SSD destroying all data on it. However, this process requires access to another Mac currently running macOS 15.7.+ Sequoia or macOS 26.x Tahoe (with the former you will need to use the Apple Configurator app). After performing a DFU Firmware Restore you will need to reinstall macOS through Internet Recovery Mode which will now hopefully work.

How to revive or restore Mac firmware - Apple Support

"How to exit Internet recovery loop and reinstall macOS on a 2018 Mac mini?"

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Getting Out of this Loop:

Await the time allotted. Once complete, use Ethernet.

When to Get Back In:

Take this as a learning experience, knowing to create a Recovery Key for your Apple Account, for instances, such as this. Note that there are requirements that must be met...

• Set Up a Recovery key for your Apple ID - Apple Support
• How to Use Account Recovery when you can’t Reset your Apple ID Password - Apple Support

How you Use Ethernet:

Being you are in a loop, use Ethernet. If you have no Ethernet port that is working, then you'd need an adapter: Use Adapters with your Mac mini - Apple Support. Which adapter to use: Belkin USB-C to 2.5Gb Ethernet Adapter - Apple

Hi,

As HWTech suggests, to exit an Internet Recovery loop and reinstall macOS on your 2018 Mac mini, clear the NVRAM, erase your drive in Disk Utility, and run the standard macOS Reinstall. If the loop persists, you will need to revive or restore the Mac's T2 security chip using another Mac.

I recommend reformat the drive before reinstall macOS.

Why were you trying to reinstall macOS from a flash drive....?

Is this your Mac mini or a used Mac mini that you just purchased...?

What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

If this is your Mac mini, you should have followed the Erase All Content and Settings directions.

Erase your Mac and reset it to factory settings - Apple Support

Use Disk Utility to erase an Intel-based Mac - Apple Support

How to reinstall macOS - Apple Support

If this is your Mac mini and you can not reinstall.

Make an appointment at your local AASP and have them Reinstall the macOS.

Find Locations

If this is a used Mac mini that you just purchased.

Return it to the seller for a refund and get your money back.