According to +++ THIS +++ article, some 2013 and 2014 MacBook Pro models are getting stuck on a non responsive black screen after updating to the Big Sur MaxOS. Even resetting NVRAM or SMC does not resolve the issue.

It appears there are some good reasons not to rush in with this particular update.
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Jim Fogle - 2021 BiaB (833) RB (Build 5) Ultra+ PAK
Cakewalk - Zoom MRS-8 recorder
Desktop: i7 Win 10 build 2004, 12GB ram 256GB SSD, 4 TB HDD
Laptop: i3 64bit Win 10 build 2004, 8GB ram 500GB HDD
Music at: http://fogle622.wix.com/fogle622-audio-home