If the cylinder is not moving at all and is stuck, spray with WD40 or similar, this can sometimes free the piston rod tube and the cylinder will start to work.
To check your cylinder, if you remove the hair pin which is holding the cylinder in the black cup. You can then lift the roof vent slightly, the cylinder will drop out of the cup, you can then unscrew the cylinder from the opening arm. This allows you to then test the cylinder.
If you submerge the cylinder into a hot jug of water, there is a wax inside the cylinder, when the wax feels heat it expands which pushes out the piston rod. If the piston rod expands in the heat, you will need to then cool it back down in the fridge for half an hour. Ensure the piston rod is fully home in the closed position, it can then be reconnected, it will then start to open as soon as the temperature rises.
If however the piston rod does not move/expand, this will mean that the cylinder is no longer working. The Bayliss openers carry a two year warranty, if your bayliss opener is within the warranty, please call or email us for next steps.