If the unit can not seem to focus no matter how much you adjust the lens please verify that the lens itself has not been scratched or damaged. If the lens is in good working condition then unplug the unit to remove power and wipe the lens with a cleaning cloth and a little bit of lens cleaner. But please be careful not to use too much cleaner because harsh chemicals will damage the lens. You can also replace the lens cover if the lens cannot be cleaned by hand. Lastly verify the actual connection of all the video wires and if they are secured correctly try using a different video wire to verify the unit's video wire has not gone bad.