Dell optiplex 7050 amber light

try replace cmos battery w a new CR2032 and clear cmos settings via motherboard CMOS_CLR jumper.

Blinking amber power light can mean bad PSU.  Solid amber can mean  bad MB.

How to run self-test without the test button on the PSU:

Turn off the computer.

Disconnect the power cable from the PSU, and wait for 15 seconds.

After 15 seconds, connect the power cable to the computer.

The LED light turns on for 3 seconds and then turns off.

If the BIST LED turns on, the power supply is delivering power to the computer.

If the BIST LED does not turn on or the PSU fan does not spin correctly, the power supply is not delivering power to the computer. Disconnect and reconnect the power cable to computer and try again. If the BIST LED does not turn on, contact Dell Technical Support for repair options.  Credit:  Dell PSU Self Test