Tried everything, attempted 4 times to install it and uninstalled it once because it didn't load.
Here's how it went.
First attempt. Tried to load safe mode to uninstall the program, forgot to run avastclear.exe as administrator. I used minimal safe mode. Folders were in desktop since I felt safer moving them.
Second attempt. Same as 1st, but with network mode on.
Third attempt. Same as first.
Fourth attempt. Started through normal mode the setup, booted to safe mode after being prompted to, and re-installed the program through normal mode. For some reason the UI had turned white, so I updated it and clicked Avast Antivirus again. Same thing.
Uninstalled the program, restarted and reinstalled successfully. For your information the program uninstalled successfully through avastclear.exe at fourth attempt, and ran the smart scan again.
Thank you so much!
(PS. In case the problem I had gets repeated, I should try these steps again)