mac mini m1 hdmi

I have a new mac mini m1, the basic configuration, 8gb mem and 256gb storage. After updating to the latest Big Sur 11.2, my hdmi connection to my monitors won't work. I took my mac mini to the Apple store and had one of the technicians have a go at it. As soon as he plugged everything in, it worked. The software update was complete and I was able to shut it down properly. So I'm thinking that as soon as I have the time, I'll just plug everything back in and I should have no issues. This was yesterday. I wasn't able to get to starting up my mac mini until an hour ago, made sure all plugs were secure. Unfortunately, the same issue happened. I turned my monitor on, which is only a year old, and booted up the mac mini and I get a "No Signal" displayed. I was on the phone with Apple support and was disconnected. I read online that some people were having issues too. Any help will do. If I have to go back to the Apple store, I will but hopefully someone has a solution for this. Thanks for reading!