I have a D10A installed in my near completed RV7a, this has worked faultlessly since installation 12 months ago until today. I flicked the master switch and pressed the left button on the unit to turn it on, the screen went blue as usual for about a second and then switched off, i am now unable to switch the unit on . Pressing the left button does absolutely nothing with or without the master supply on. Is there a reset switch / proceedure for reset or would removing the internal battery help? Ser no 3140. Internal battery voltage 16.2V main bus 12.2V prior to failure. Any suggestions please? Update-- I have removed the internal battery and replaced it but still the unit fails to operate.:-/