I bought a new Mini last week because the old one had a bad case of too little storage and memory, and that led me into unexpected trouble. Migration from the old Mini seemed to work well, and it showed a success. However the new one showed a blank screen. The only option I could find for support was Chat, and that wasn’t up to the job. I only had one monitor with a HDMI port and that was on the old Mini which I was using for the Chat, and there was no way to switch the new Mini to the HDMI monitor without breaking contact with the chat. Using an adapter with non-HDMI monitor had worked for the new Mini when I started the migration, so I assumed it would work after the migration to the new Mini and Sequoia was complete. After well over an hour of fruitless effort I told the Chat I wanted to go to an Apple Store for help. Fortunately there are 3 or 4 within 15 miles.
The next morning I hooked the new Mini up to my only HDMI Monitor and was surprised and encouraged to see the Sequoia startup screen, but only for a few seconds, then back to a black screen. When I got to the Apple Store, the tech used one of my HDMI cables to hook it into one of their monitors and it worked perfectly. He blamed the problem on my use of HDMI adapter and to connect to the old monitor, and I agreed.
The experience gave me three lessons. One is that Chat on a screen can be a very ineffective way to communicate about some problems; the support person used some terms I didn’t understand. A second is that I should have checked my equipment to be sure I had two HDMI-equipped monitors and more USC connectors. A third is that either Sequoia, the new Mini, or the connectors are significantly more fussy about connections than Sonoma, the old Mini and the monitor that required an HTMI adapter.