The batteries are flat in the Genius Radiator Valve and the valve will have stopped working altogether.
Remove the battery cover. Do this by placing a fingernail at the bottom of the battery cover, pulling the catch up (in the direction of the screen) and compressing the slit next to the catch. The battery cover hinges at the screen end of the valve.
Remove the 2 x AA batteries, (note the orientation of the batteries, one is up and one is down).
Wait 30 seconds before putting in the new batteries.
Rechargeable batteries should not be used as their voltage is too low (1.2v not 1.5v).
Put in the 2 new AA batteries, take note of the orientation shown on the screen.
Select the Genius Radiator Valve with the flat batteryThe old number for the Genius Radiator Valve may be on the back of the device.
Wake up the Genius Radiator Valve by short pressing one of the arrow buttons once.