Hello, I have a Dell XPS 8940 which I purchased in 2020. The 500W PSU appears to be failed. When the power line cord is first plugged-in, the green light on the back of the PSU lights-up for 3 seconds then goes out and stays out. I get no response to pushing the front panel power button.

Where can I get a replacement PSU? The Dell part number on the label is Y7R0X 

If this PSU cannot be purchased directly from Dell, then who is a reputable seller for this item?