Inside the dashcam, there are two stacked circuit boards. Using a plastic pry or spudger tool, gently pry the top circuit board up from the bottom circuit board.

There are 3 connectors between the 2 circuit boards holding them together. In the 2nd photo, for reference you can see these 3 connectors (outlined in red), once the boards have been separated. You can also see the bottom side of the upper circuit board here, where the RTC battery is found.