Chosen Solution

When I open the camera app, front camera works fine but when I switch to the back camera the display goes black. In the top left corner it shows the following message, “Flash is Disabled - The iPhone needs to cool down before you can use the flash.” But the phones temperature feels normal.

Have you tried to replace the camera? iPhone 5s Rear Facing Camera Replacement If yes, try these steps:

  1. Go to Options
  2. General
  3. Restore and select reset settings

I have this same problem I tried to replace the back camera but it didn’t solve the problem

You need to replace the flash module, the clue is in the error message lol. The flash module is part of the power button cable.

If flash work when it is cold then most likley your cam is defect and you have to place a new back-camera.