First, check to see if the flash is turned on. The flash button is a small lightning bolt on the back face. Also, visit your camera manual to troubleshoot this issue, as sensor or software problems can arise. If this does not help, your filament must be replaced. See the repair guide on the Nikon Coolpix AW130 home page.
First, try to charge the Nikon for the recommended amount of time. Try an alternative electrical port. If this does not work, your battery needs to be replaced. Each additional charge will naturally wear down the battery. See the repair guide on the Nikon Coolpix AW130 home page.
Eposure is difficult to control in point and shoot cameras. The shutter speed is way too fast, especially in bright sunlight. This makes the video "flicker" or "stutter." Try changing the recording rate or using a different camera setting. Unfortunately, since this camera is relatively basic with a focus on underwater photos, there isn't much that can be done to resolve this issue.