iPhone 7 Boot Loop issue with Front Camera/Proximity sensor/Ear Piece Flex

"Ideally, you have to try a known-good FCAM flex. Small parts can be hit or miss, especially for something as new as an iPhone 7. If you don't have access to a known-good part, then the logic board needs to be verified to try and eliminate something.

What's probably happening is that one of those elements (CAM/PROX/ALS) of the circuit is defective. Once the flex is connected, it may be drawing too much current and forcing the some other power rails into current limiting mode. This will have to be looked at by a micro-solderer."

"I would try a complete assembly from a working phone, if available. In other words, try with a known good complete assembly. Sometimes new ones are bad too like mentioned by others here.

Also make sure you are connecting it in the correct orientation.

Finally, connect the front cam assembly without plugging the home button extension cable onto the board, see if that changes anything.

Only if using a known good assembly in the correct orientation yields the same result, can you then conclude that you have a board level problem.

Note: continuous boot looping may cause data corruption. Pull a back-up before testing any further."

Just in case anyone finds this question and possibly did the same thing as me, check to make sure you’re putting the cable the right way…. I tried putting it in upside down because I wasn’t following the guide as I thought I knew what I was doing… Found that out after I bought a new sensor/camera cable.

"I had issues with sensorflex as well, first replacement resulted in bootloop, second replacement, no speaker, no proximity

I just fixed these two sensorflex by re-soldering the contacts under the sticker, the factory soldering was bad, even on the flex that I pulled from the original phone

Also the proximity frame on the new display “OEM quality” did not align with the sensor “eyes”"

"Not sure if solved yet, but I had this exact issue, phone will bootloop, but when sensor flex is disconnected it will boot up fine. Strangely enough this was due to a small tear in the flex cable that connects the home button to the board. And when this cable is disconnected the phone boots fine even with sensor flex connected.

Hope this helps"

I had struggled with this problem but found a different issue that solved my troubles, there is a screw that sits above the front camera housing on the screen. See yellow circle in the attached image. This was missing in the new screen. once replaced the phone booted up straight away.