When you dis- and reconnected the rear camera module, were you able to check both “click” connectors? There are two, one is visible and connects right to the module, the other is hidden under the metal plate, roughly under the camera symbol here.
If your camera module is the original one that the FP3 (without the plus) came with, there is a legion of offers of those here in the forum’s marketplace, often just for shipping costs:
