Follow each step carefully.
Position the TrueDepth camera assembly back into its housing.
Align the camera cable with the connector on the motherboard and press down firmly to connect.
Use a Pentalobe screwdriver to secure the camera assembly with the screws removed earlier.
Align the battery connector with the motherboard and press down until it clicks into place.
Align the device case with the edges of the device and press down until it snaps into place.
Press and hold the power button until the device powers on.