Perform a Hard Power Cycle and Pin-Level Voltage Verification

Since the power delivery is disrupted, perform these steps to isolate the fault before replacing major components:

1. Ensure the battery is fully charged and the physical power switch is set to ON.
2. Perform a hard reset: Disconnect the battery from the controller, hold the 'M' button on the display for 15 seconds to drain residual capacitor charge, then reconnect the battery and attempt to power on.
3. Using a multimeter set to DC voltage, back-probe the Red (VCC) and Black (GND) pins on the display connector while the battery is connected.
4. If the multimeter reads 0V, inspect the 1T4 cable junction at the controller for loose pins or corrosion.
5. If the multimeter reads the correct battery voltage (e.g., 36V or 48V) but the display remains dark, the internal power regulation circuit of the display has failed, confirming the need for a unit replacement.

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