This is a picture of my dashcam internals.
It seems to work fine when plugged in at home so I’m guessing car vibrations have compromised a solder connection.
Nothing looks bad besides what appear to be burn marks around the connections to the small batteries and the speaker.
In diagnostic attempts, I can consistently force power interruption by wiggling the mini usb power cable. I do get 5v across the mini USB connection when leaving it still.