I updated two weeks ago and after a trip to the Genius Bar, four Apple Care sessions and a third party shop and I now own a $2000 brick of garbage.
My unit (early 2019) will not recognize a charger (it always shows charging even while unplugged). Unit all of the sudden it goes to 5% and powers off. We have tried everything. But without a SMC reset every few hours the unit is a brick.
Here are all the steps we have taken and are no closer to a resolution.
Use Time Machine to go back and restore - maybe but after the update all my Time Machine files have disappeared.
Restoring to original settings - nope as the unit when trying to restore can't find its own hard drive.
Reinstall Big Sur - each time the problem gets worse and the SMC reset is required more often.
Reinstall Catalina from an external hard drive - fat chance - the unit no longer recognizes external drives (after the last stab at reinstalling Big Sur)
Try a new charger - four times and nope.
Have Genius bar do diagnostics and see if it is hardware - no hardware problems detected - odd when they see the unit says it is charging while not plugged in. Big Sur must have magic in it.
The latest was taking it to an Apple Certified shop (recommended by Apple) - they found that the unit will see SD cards, but nothing else you plug in - so they are suggesting downloading Catalina to an SD then trying to boot from that. BUT of course Apple Care and Apple Warranty does not cover software issues - and since this is a software issue ... I have to pay out of pocket. Seriously Apple screwed this up and will not cover fixing it!
Best part is when I take it in to fix it - the unit no longer shows on Find My.
Out of principle I just can't see paying someone to un-Apple my computer.
Apple needs to quit lying about Big Sur and do the right thing. Admit it is a total failure and roll it back.
There is an update that just became available - should I trust it?