Then check the Startup Disk, Display, and Date & Time panes of SystemPreferences to make sure they’re set the way you want them.If you have an older Mac that chimes at boot, hold down the keys until you hear a second startup chime. Then let go and allow your Mac to continue starting normally. Keep holding down those keys for about 20 seconds.Press the power button, and as soon as you power up the laptop, hold down Command-Option-P-R.To reset your NVRAM, you use exactly the same procedure you once used to reset PRAM. Wait 5 seconds, then press the power button again to turn on your Mac.

If that doesn’t resolve the issue, follow these steps:

Press the power button again to turn on your Mac.

Release the power button, then wait a few seconds.

Press and hold its power button for 10 seconds.

Choose Apple menu > Shut Down and wait for your Mac to shut down.

Mac desktop computers with the T2 chip Try this first: I finally got it working!! I'll explain what I did in order to help other people Remember this is only for T2 iMac 2020.įollow these instructions for Mac computers that have the Apple T2 Security Chip. What can I do? Please I need some serious help apparently. I've also changed the security for my T2 chip to none security and able to boot from a usb external, but it didnt work.

I did what they told me: reinstall big sur and without any other installation previous to WIndows, it didn't work either. I've called Apple support and they won't gave me any solution. One for Machintosh HD and two for Windows. Nothing can be done, installation is stopped and the only way is manually stop iMac and even if you press option key to see different starting systems, there are 3.

it restarts, appears for a few seconds the windows logo and the animation points below but it apparently crashes and stays in A BLACK SCREEN. After this, it needs a restart which gives you 10 seconds. After restart, it appears Windows setup configuration and it begings to install passing all the ticks at the first installation window. I start Bootcamp, select ISO file, it downloads everything and restart the iMac. I'm also using the WINDOWS 10 21H1 ISO file downloaded from the Windows site. I want to install Windows 10 Pro using Bootcamp and giving a total of 370Gb into the Windows partition, which is enough. It has macOS Big Sur 11.4 with this specs:ģ,6GHz Intel Core i9 10n., 8GB 2667 MHz DDR4 RAM, AMD Radeon Pro 5700 XT 16GB and a 1TB os SSD Storage. I've just recently bought last week a new 27'inc iMac 5k retina, 2020. I'm posting this because I'm running out of solutions and I need serious help.

Bootcamp install windows 10