If the device camera stop working and cannot be turned ON, or it only shows some errors including a blank or black screen display. You may refer this solution below after confirming that the problem not lies on software problem.
Nokia 6124c Not Working Camera Problem Solution
Then check the two DC to DC voltage converter and regulator chips.
These chips supply the voltage to the Camera Accelerator IC. You may first try to check the input voltage 3.7 volts, this voltage feeds from the VBAT (battery voltage) line path. Then the output voltages, if there is no output voltage reading, it means that there is a problem on that certain DC converter chip. Replace it if necessary.
If the two supply voltages (1.8V and 2.8V) to the camera IC were both okay, check the camera clock components such as the 47 ohms resistor and the 27 pica-farad capacitor.
You may then try to re-heat or rework the camera accelerator chip or replace it if already found faulty or damaged.