Please follow the steps below:
1.Cover the lens with the cap or black cloth to make sure it is total dark；
2. Get a tweezer and make the two pins of the tweezer respectively touched to the two components LT and ER, circled out as below;
3. Power up your camera. After 3 seconds, remove the tweezer but keep the camera powered up.
4. After about 1 minute, restart the camera.