Separate the camera preview from the phone display
A black camera preview inside an otherwise usable phone is different from a completely black display. Note whether menus remain visible, whether the app opens, and whether the issue affects the front camera, rear camera or both. Do not begin by treating every dark image as a failed display or a failed camera module.
Ask what happened immediately before the problem: a fall, a repair, an app change or an ordinary software update. Record the answer without deciding that the most recent event must have caused the fault. A useful history establishes the order of events and keeps uncertain connections visible.
Make a controlled comparison
Apple's camera guidance includes checking accessories and comparing camera behaviour. Follow the exact device instructions for any restart or software check. Remove an easily detachable accessory only when doing so is safe and repeat the same test, rather than changing several settings and attachments together.
Compare front and rear cameras and, where the phone supports it, the affected camera modes. Use a plain test scene that contains no private documents, faces or account information. Describe whether the preview is black, frozen, blurred or marked by an error; those are different observations.
Avoid destructive experiments
Do not erase the phone, install unofficial firmware or open it simply because a restart did not help. A software change may affect data and settings without answering the camera question. Internal inspection requires model-specific handling, suitable tools and an agreed service scope.
After a previous repair, tell the next technician exactly what was changed if that information is available. Guessing that a connector is loose and repeatedly pressing on the camera area is not a substitute for inspection. It can also damage the device and confuse the original symptom.
Define the checks needed for handover
A camera repair should be assessed against the complaint: preview, capture, focus, switching cameras and saving a test image, as supported by that model. If video or flash was part of the problem, include it in the agreed checks. Obtain permission before using any customer account or personal gallery.
For a student, the strongest case note shows the original failure, the comparisons performed and the verified result. Use your own permitted test images and describe remaining limitations honestly. A single successful photo does not establish that every camera feature works.
Sources and further reading
Manufacturer and technical references for the checks discussed in this guide. Follow the instructions for your exact device and equipment.
Repair procedures involve heat, electricity, fragile parts and customer data. Practise under qualified supervision and work only on devices you are authorized to service.
