Measure the crystal oscillator near the SIO/EC chip using an oscilloscope to ensure it oscillates at .
Short circuit on a secondary voltage rail (e.g., CPU, RAM, or PCH rails) causing the system to trigger over-current protection (OCP). Diagnostic Steps: Remove the CPU and RAM modules. Test the board again. Lm495 Mb 11269-2 Schematic Download Fixed
If the standby voltages are present but the power button yields zero reaction, flashing the dedicated EC ROM chip often fixes the dead state. How to Safely Utilize the Schematic Files Measure the crystal oscillator near the SIO/EC chip