Apple acknowledged that there was a problem installing macOS Big Sur with some MacBook Pros. We are not talking about a small bug that can be slipped under the carpet: during the process, the screen goes black and there is nothing more to do (read: The installation of macOS Big Sur goes wrong with owners of 13-inch MacBook Pro (2013/2014)).
In assistance sheet, the manufacturer details the symptoms: the macOS Big Sur installer warns that the update cannot be carried out on the machine, or the Mac may block on a black screen, or it may present a forbidden icon 🚫. If the computer fails to restart, Apple recommends the following steps:
- press and hold the Mac’s power button for at least ten seconds, then release it. If the Mac was on, it will turn off.
- Disconnect all external peripherals (monitors, USB accessories, SDXC cards). Then turn on the Mac.
- If the problem persists, Apple offers to reset the SMC (follow this procedure).
- Otherwise, we can try to reset NVRAM or PRAM (procedure).
And if none of that works, the only solution right now is to turn to Apple support. The manufacturer specifies that he will update the sheet as soon as he has more information.