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Mac Couldn't Startup and Even Won't Reinstall macOS

Recently I downloaded Sophos antivirus in order to perform a virus scan on my 2017 iMac with a fusion drive and macOS Mojave. I also use the Handbrake firewall. This morning when I installed a new Wacom graphic tablet, it asked me to restart my computer and I also did that. However, I got stuck at the startup bar for around an hour. I've tried to force restart the machine, enter Safe Mode, unplug all accessories, and run First Aid in Recovery Mode, but all failed. And I even failed to reinstall macOS. I followed the Apple support's guide to reinstall macOS from Internet Recovery Mode, still failed and got the error 'PKDownloadError error 8'. I even ran Apple Diagnostics, and no issues found. Then, I got a black screen with a prohibitory symbol. Any help?

Best Answered by

iBoysoft author Connie Yang

Connie Yang

Answered on Wednesday, November 22, 2023

From your description, I can see that your Mac doesn't have any hardware issues as the Apple Diagnostics result shows nothing wrong. The first time that your Mac won't restart is probably caused by the third-party antivirus.

The reason why your Mac shows a prohibitory symbol on startup is that your macOS reinstallation process failed. At present, no functioning operating system on your Mac startup disk.

Since you've tried all possible ways but still can't fix the unbootable Mac machine, your last and only choice is to erase your Mac and then reinstall macOS. In other words, to factory reset your Mac.

But resetting your Mac will ease all content on it. If your Mac contains a lot of files that haven't been backed up, you can use iBoysoft Mac Recovery Mode to rescue your data first. This special mode can help you recover files from an unbootable Mac easily and quickly.

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