I had my primary screen go down and reboot several times on Fiske approach to Oshkosh this year. Not the best time to happen. Provided them diagnostics at the show and they said low voltage (assumed because of low rpm and everything on including landing lights). Provided to Dynon tech support later and they said they recorded voltage going to zero. Not possible since I have a backup battery and the secondary screen without a backup stayed up. Sound like I may have the same issue but it has not happened since. Am installing a battery on the secondary screen for backup at annual.
Do you have backup batteries on one or both screens?
Scott- 2020 donation
New RV-7A N579RV, finally over 40 hours... the leash is off
Built RV-12, 328 hours-sold, purchased RV-12 sold, Built RV-9A, 536 hours-sold, Not completed RV-7 sold, Built Kitfox sold