Trying to upgrade from El Capitan to Sierra - monitor goes to sleep permanently

[Samjaka]

When Sierra came out, I tried to upgrade to it, but my monitor just showed nothing. When I used CMD+R and restarted from there, I could access Mac. Eventually had technician reinstall El Capitan, because no advice I read helped.

Tried upgrading to Sierra again (using the Sierra button that sits on my Launchpad for a year) and this time it got even worse. I can access CMD+R, but restart from there has no effect.

I use Philips minotor, where power button blinks when it is asleep. After upgrading to Sierra, it had same effect - monitor seems to be asleep, while Mac is running.

Used back up to revert back to El Capitan. Sierra has brought nothing but troubles. Now even El Capitan seems bit slower than before. I hope nothing got damaged during Sierra upgrade and back-up restore?

Any ideas of why this could have happened? Is it due to monitor not being Apple hardware? Sierra just not working with my Mac Mini?

 

[Audit13]

Are you able to try another monitor?

 

[Samjaka]

Are you able to try another monitor?

Unfortuantely I only have one.
I considered buying apple hadware monitor, but those are expensive and I'm bit irritated to buy apple hardware monitor that might not even work without knowing what the exact issue is.

 

[ctrlzone]

When Sierra came out, I tried to upgrade to it, but my monitor just showed nothing. When I used CMD+R and restarted from there, I could access Mac. Eventually had technician reinstall El Capitan, because no advice I read helped.

Tried upgrading to Sierra again (using the Sierra button that sits on my Launchpad for a year) and this time it got even worse. I can access CMD+R, but restart from there has no effect.

I use Philips minotor, where power button blinks when it is asleep. After upgrading to Sierra, it had same effect - monitor seems to be asleep, while Mac is running.

Used back up to revert back to El Capitan. Sierra has brought nothing but troubles. Now even El Capitan seems bit slower than before. I hope nothing got damaged during Sierra upgrade and back-up restore?

Any ideas of why this could have happened? Is it due to monitor not being Apple hardware? Sierra just not working with my Mac Mini?

this is strange
what machine do you have ?

 

[Audit13]

Could it be a cable issue? Does it matter which version of Sierra is installed? Happens on a clean install too? Maybe install Sierra to an external and leave a working version of El Cap on the machine?

 

[DeltaMac]

Hmmm... If you tried upgrading from the "Sierra button that sits on my Launchpad for a year", that likely means that you still have the exact same installer that you originally downloaded, still on your Mac. Look in the Applications folder for an app named "Install macOS Sierra". Drag that to the trash, and empty the trash (so it is deleted completely from your Mac!)
Now, download again from the App Store. That will assure that you have the most current installer app, and may let you upgrade without issues this time.
Even better --- don't install from that downloaded installer. Just quit the installer when it launches at the end of the download. Use that downloaded installer to make a bootable

 

[HDFan]

Can you connect to the Mac with Sierra remotely via something like Parallels Access, VNC, Apple's remote desktop? If you can maybe there is some setting in Preferences/Displays that is causing problems?