DTC C2703-54: Control Module Slave Missing Calibration: General Description
WARNING: This page is about a different car, the 2021 Kia Seltos. However, it is still accessible from the selected car via links, so may be relevant.
The BCW ECU monitors battery voltage input ignition voltage.
When the voltage is higher than the expected normal value, this code is set, and the BCW switch LED functions are prohibited.