Plan A........Flat screw bit witha socket and ratchet
Plan B.......Sharp chisel and catch the edge to move the fastener in the loosening direction.
Plan C......https://www.northerntool.com/shop/tools/product_36882_36882?cm_mmc=Google-pla&utm_source=Google_PLA&utm_medium=Hand%20Tools%20%3E%20Screw%20%2B%20Nut%20Drivers&utm_campaign=GRIP&utm_content=15825&&gclid=CjwKCAjw9L_tBRBXEiwAOWVVCSWWAVolkcAISopU6ej6ZpUTvp0PL7bIJcAYn6MBuLvUArTKgIdxyxoCdRgQAvD_BwE
