I have a Siemens RDH10RF model (with a wireless link between the receiver installed near the boiler and the remote transmitter unit) which has just started doing exactly the same as yours. At first the light was on "red" instead of "green" which indicates a pairing/communication failure however I could still get the boiler to fire by pressing the "over ride" button on the receiver plus the led indicating the relay contacts had activated would also illuminate. However, after about 4 days of this it's now gone totally dead with no lights and no response to the override - but provided the mains power is on to the receiver the relay contacts are permanently closed and the boiler will fire. I intend to dismantle the receiver unit and as a long shot look for obvious circuit board damage/fried components etc. But blown circuit board fuse is probably the only easily user replaceable component - if a fuse exists - so frankly I'm not confident of being able to resuscitate it! Regrettably, it's probably irepairable 'cos most/all the components will be super-small SMD types and the "relay" will be an IC not electro-mechanical, so pcb level repairs may be a no-no. So.....unless it's a blown on-board fuse it's dead!
C Bell, December 2014
