If that kit has a small enough bit to fit on the bolt. Use an impact driver with it. The type you use with a hammer. Put the bit on a small extension to impact driver. Using a hammer, Tap on the end of the driver, while twisting it with your hand. Should loosen up. I've done this with screws on motorcycle cases for years
https://www.amazon.com/Vessel-NO-250...71485441&psc=1