I have a T2984 which will not boot up. I opened up the T2984 and shorted across the switch but confirmed that is not it. What confuses me is that there is a green LED that is lit on the mobo when the power supply is plugged in. Is that telling me that the power supply is good, but that because the mobo is bad, I cannot start up? I am not sure, as I have heard that there are multiple output levels from a power supply. Perhaps the 3.3v is working, and the 12v is not?

I do not have a replacement power supply (only some older ones without the square 4 pin connector), as I am considering simply upgrading to a new system. I was hoping to make an informed decision about whether to buy a new power supply or not.

Thanks for any advice you might have!

Fork it out for the PSU. The green led is just confirming that you have 12vdc. which drives the drives, most of the mobo uses a lo volt ac, if it's not there you're out a PSU if you're outside warranty. Unless you're an electronics tech their's no fix, even so, it's not usually worth the effort.