A Isuzu DMAX equipped with the 4jj1 engine was brought to us in a no start condition, which also had no sign of the engine light - meaning the ECU was not communicating with the rest of the system, we diagnosed the vehicle with the right equipment by first performing an OBD scan which resulted in no communication with ECU but communication with the rest of the vehicle's modules was present, we then checked for power supply to the ECM and found out that the vehicle's terminal 30/constant power supply was severely lacking voltage, measuring 5v when it should be 11-14v, this was resolved by replacing the relay causing the voltage drop, but still no sign of check engine light.
After looking at CAN communication at the DLC, it was found that the ECU itself was unresponsive, which then resulted us testing the ECU on bench, the ECU likely suffered processor damage from the voltage spikes because the ECU did not respond on bench, then later the client was informed about the situation, the client then ordered a brand new control unit according to chassis number which we then programmed to the vehicle using the right equipment, the vehicle is back on the road now.