There was a reply from Support4 here but I don’t know where it is now. Here is a copy . . .
HI there
Glad to help, Sorry for the trouble when using.
Please try some solutions here :
CLR CMOS
First, please unplug the power supply and HDMI cable.
Secondly, Please hit the “CLR CMOS” button for about 10 seconds.
Please wait until 10 minutes later (THIS IS VERY IMPORTANT),
Then plug the power supply and HDMI cable back in, turn on the PC again,
once turn on the PC, you will need more than one minute to wait for the PC to enter the system.
See if it works. Please try few more times.
Reset
Start your PC, just as Windows attempts to load (spinning dots), press and hold Power Button for 5 - 10 seconds to perform a Hard Shut Down
Do this twice
On the third start Windows will boot into the Recovery Environment and from there you can access System Repair, Safe Mode, Command Prompt . . . etc.
Please try each option one at a time, then see if Windows will boot . . .
Go to Troubleshoot - Advanced Option - Startup Repair
See if Windows startup can repair itself
Go to Troubleshoot - Advanced Option - System Restore
Check to see if you have a restore point you can go back to
If you do not have a Restore Point, go to Troubleshoot - Advanced Option - Startup Settings and click Restart
Upon restart, press 4 to enter Safe Mode
Once in Safe Mode, backup your data if you do not already have a backup
Open Device Manager and check to make sure all your Drivers are up to date
Reboot to see if Windows will start Normally
If the above fails, go to Troubleshoot - Advanced Options - Reset this PC
Choose to keep your files and apps, just your files or to keep nothing
Then start the Reset