Position the new battery over the circuit board so its terminals line up with the corresponding pads on the circuit board.

Solder the new battery to the circuit board, being careful not to overheat the circuit board traces nor create any shorts.

Slide the rubber tubing/insulation onto the new battery.

Carefully align and reconnect the 3 connectors between the two stacked circuit boards together, then reassemble the dashcam body and you're done!