After opening Steam, I got one of the bottom-right corner messages from Avast. It was something along the lines of "potential malware detected, boot in safe mode/sandbox" (I didn't memorize the wording, sorry I can't be more specific). I didn't think much of it, but I thought I'd rather be safe than sorry and clicked 'okay'. Pretty soon, my screen went black, presumably as part of the boot.
The screen remained black for ~half an hour, then I accidentally pulled the power plug out (the flex is taut, I should really buy a longer one). I turned it on again, and left it on for hours, but my screen is still displaying 'No Signal' and going black wherever turned on. No idea what's wrong. Yes, I've tried using a different HDMI socket/cable. Is Avast the issue, or is it more likely some hardware component has failed, and by chance this occurred while Avast was doing the reboot?
Thanks in advance for any advice.