I have a set of three BT3440 cordless phones. One of them has stopped working. It just emits a feint beep sound and there is no display on the handset. It is not the base station or the charger at fault as I have tried the other handsets on the charger unit and they are fine. Nor is it a battery problem as I have tried different batteries and it still does not work. When I put the handset on the charger a feint beeping sound is heard but no full display and buttons are inoperative. comes on again. Any suggestions?? I need to know if there is anyway to completely reset the HANDSET ONLY ??? Or does anyone have an old handset they can sell me cheap?? Also, are there any other BT handsets that would be compatible in case I have to find a replacement.