Problem with Dynon Booting up

[BigFlapper]

On 2 occasions recently I have had a problem with my Dynon classic not booting up when I turn on the power. Both have been after I flew somewhere and about one hour has passed.
It has never been a problem up after sitting idle for a number of days.
When it does finally start up Dynon shows a voltage of 12.8 volts.
I have a tested backup Dynon backup battery installed.
Any suggestions or areas to check will be appreciated.

 

[Dynon]

One troubleshooting step is hitting the "reset" combination of keys, which are buttons 1,2,5 simultaneously when power is applied but they're not booting up. Does that change anything?

 

[BigFlapper]

I have not tried that.
I will certainly try resetting next time I have the problem.
Thanks