My RDH10 rf is not working?

Siemans RDF 10RF wall digital room display to raise the temperature but nothing, even after several hours! Replaced batteries, again nothing. Pressed the test and then the reset button at the rear, nothing. I now have a blank display screen. The RCR10/433 receiver is also non active even though I have pressed the reset( other than a flashing light) and test buttons. Thanks