First, avoid the manual update for this tests. Let Avast update itself whenever it is ready.

Second, the “key” of the above instructions is not to uninstall and reinstall. The “key” is the removal utility for Avast, running it from Windows Safe Mode.

Even after the removal utility, you may search for “avast” and “alwil” and delete any folder with such name (unless you have created such folder for your personal needs).