Inspection Procedure 4: Multimode keyless entry system function does not work at all <Vehicles with electric retractable remote controlled door mirrors>: Notes
WARNING: This page is about a different car, the 2018 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.