XPS 8940 PSU's: 2VD0G 360W LiteOn, E-Star, Bronze5K7J8 500W Delta, E-Star99TPH 500W LiteOn, E-StarY7R0X 500W Chicony  
I purchased a 8940 desktop in December 2021. I could turn my computer on yesterday. I performed all of the power supply tests recommended by Dell but I could not get any response from the computer. I suspect that a new power supply is in order. My current power supply model number is L500EPM and the dell P\N is 99TPH. I have 2 questions, is it common for a power supply to fail after only 1.5 years? Where can I order a new power supply? I have been unsuccessful finding a compatible power supply. Any help would be appreciated
XPS 8940, power supply 99TPH