likley that the solenoid valve is not opening to allow the water through. The humming sound is the solenoid coil operating. Check the water inlet filter make sure its not blocked. Then open up solenoid valve and make sure there is not dirt or scale inside. If unsure about doing this ask a repairerer to take alook
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix baths and showers.