Hi HHallett,
Since you have already tried all the possible troubleshooting steps to resolve this issue, I would recommend you to check with a different power supply (if available). If the issue persists, the motherboard may need a replacement. You mentioned that the power button light is amber; Is it blinking amber or solid amber? You can refer to the chart mentioned below:
![]() | Blinking amber | The computer is receiving electrical power, and power supplied by the power supply is normal. A device might be malfunctioning or incorrectly installed. |
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![]() | Steady amber | This is a system fault error condition, including the power supply. Only the +5VSB rail on the power supply is working correctly. |
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Please reply if you have any questions.