Hello,  I just got the A6700, with underwater housing and Turtle trigger. Same issue as described, when the trigger is connected, the camera considers there is always a strobe « On » and impossible to disable it from the menu, strobe always in « force » mode. Latest firmware downloaded, not better.Only solution to use the full automatic mode, like on a smartphone…I will try to use a mini strobe instead the trigger. 

I'm looking for someone who has a Sony A7/A7R/A7S with the Play Memories multi-exposure app who would like to help back it up to the Internet Archive. ir u want to help Plz contacto me

I am a bit confused by your setup but anyway, I don't know of any cameras that can be turned on and off remotely. Most cameras would have a setting to turn off after a certain amount of time if not used however.