blank display on AM10

FB

<span style="font-size:12pt">A Buderus GB142-24 was making DHW but no space heat to the rads.  </span><span style="font-size:12pt">The AM10 had worked for several years but now the display was blank.</span><span style="font-size:12pt">  </span><span style="font-size:12pt">After powering down, disconnecting the AM10, moving the potential-free thermostat</span><span style="font-size:12pt">  </span><span style="font-size:12pt">wires from the AM10 "On/Off" terminal to the WA terminal, and powering up, the system went to work.</span><span style="font-size:12pt">  </span><span style="font-size:12pt">Instead of modulating from the outdoor reset, they rad water temp is now controlled by the space heating temperature knob, set to 165 degrees.</span><span style="font-size:12pt">  </span><span style="font-size:12pt">With the AM10 display going blank, would you replace the AM10 or do other testing?</span><span style="font-size:12pt">     </span>