First, I meant to say in my post above "Replacement PSU's are fairly easy to get," not "rarely."  I'll edit it. That is a possibility.  On PSU's with the test button, a bad PSU with the test button pushed can still light the green light and power the fans, depending on how bad it is.  In the case of your 3050, it doesn't seem to be getting power, if any. If the MB were bad, which seems more rare than a bad PSU, the 3050 woukd at least be giving you a blink code thru the power light.  There hasn't been any power light blink codes leading us to another PC component. In come cases, blinking amber power light can mean bad PSU, and solid amber bad MB or bad MB component (CPU, etc.).  But your 3050 hasn't been doing that either.  If a PSU is bad enough, like dead for example, a blink code won't happen.  PSU's also show other signs of going out. From what I can tell, you removed the things redxps630 wanted you to, yet, when applying power and attempting to power on, no green light that stayed on.  Through all of this, the 3050 has mostly been playing dead except for 3 sec. of green light.
I have an Optiplex 3050 SFF  that when plugged in I get the green led for a few seconds but the unit won't power on. The only indication that I have power going to the unit is the green led for a few seconds. I tried removing the CMOS battery for 15 minutes and no change. Any suggestions would be appreciated.
Optiplex 3050 SFF Won't power on