The brake can be manually disengaged by turning the lever left or right just a bit. Less than 5 degrees will do it. Looking at the top of the manual brake lever you can see a couple of indentations. Those line up with holes in the cylinderical brake body. By rotating the handle the indentations bring the handle up by about 2 mm, compressing the internal spring and releasing the brake.
Another good brake trick is the method we sometimes use to make sure the electrical brake action is working. There is a small motion of the manual brake lever every time the brake is electrically released. The motion is so small it's hard to see. If you set a small coin or washer on the manual actuation handle, you should see the coin flip off when the machine is turned on. This is a positive indication of the brake release.