My suggestion:

Reboot TWICE.

Download Online Armor Firewall again and install it again.

Reboot once into Windows Normal Mode (please do no skip this first reboot), and then reboot again but into Windows Safe Mode.

As per the instructions in OA’s website, use the Control Panel “Add/Remove Programs” applet from Windows Safe Mode to uninstall OA.

Reboot into Windows Normal Mode and test AIS. If for some reason it still is not working correctly, go to Control Panel “Add/Remove Programs” → Avast → Repair Avast. Once the repair completed, please REBOOT immediately before testing or changing anything else.

In addition, it might be recommended to delete the firewall rules too and re-create them anew (so to avoid additional potential problems).