Avast won't open or scan!!

I have Avast Free on Windows 10 HP laptop and I noticed today that my system was oddly sluggish. When I went to scan I saw that the tray icon had not loaded. I tried opening Avast, shutting down the computer, and even reinstalling, but nothing is working. The tray will never load automatically when the computer starts, the main desktop icon will not load the Avast user interface for more than a fraction of a second before it disappears, and when I CAN get to the scan button in that time, it gets to 6% and vanishes. And when I open my.avast.com This machine is not listed. I’m not even sure what to try at this point.

Did you remove avast using https://www.avast.com/uninstall-utility
Any other security software you have now or ever had?
If removed how was it removed?