als — I2C bus

The i2c bus can no longer communicate with the ambient light sensor, mounted on the same flex as the front camera. Confirmed iPhone 7 case: with the front camera replaced, the device boots normally.

iPhone

Front camera flex / ambient light sensor (ALS)

Medium confidenceVerified sourceI2C bus

First check

Boot with the front camera disconnected: if the boot loop disappears, replace the front camera/sensors flex.

Sources