No display after MacOS big sur install - Mac mini 2018

I successfully downloaded and installed big sur, but after system asked me to restart it never appeared with a display.

after and hour I tried a restart proceeding with SMC and NVRAM resets, even tried usb-c hdmi dongle for display instead of hdmi port, not seems to work.

any ideas...?
Same thing happened to my Mac mini system. After fighting it for one hour, spent the next six hours reverting to Catalina. All OK now, and HDMI now works.
No display after MacOS big sur install - Mac mini 2018
 
 
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