HP DPS-1200FB power supply wont stay on. Help w/diag, please.

[VoltJesus]

Ok gentlemen, I am requesting technical assistance on an HP DPS-1200FB server power supply.

Now I bought 2 of these several months ago. I tested both with a 1k resistor on pins 33 and 37 to make sure they were not DOA after the shipment came in.
Both units showed 12+ volts when checking the outputs, so I thought all was good. I did not have anything 12v I could use as a load to test them for max output. Never considered that they might fail to operate, even after I saw both of them power up and show 12v on the outputs.

Ok, fast forward to a few days ago. I finally finished building my massive battery pack, and was in the stage of building my charging setup.
Since the charge controller I am going to use works more efficiently at 24v than at 12v, I needed to modify one of the power supplies so they could run in series.
So I took one apart and did the "output float mod". Finished it up and it works fine. I've even charged my battery pack (although, much slower) with just the one supply running 12v into my charge controller.

The one that I did not touch refuses to power up. Now, to be specific, when you attach a resistor to pins 33 and 37, it powers up for a brief moment, then the voltage starts to drop off. Seems like there is a safety built into one of the boards that shuts it down. Why that is, I have no idea.
I've tried to do some searching to see if there was any way I could diagnose the issue, but I am coming up short.

Is there anyone that knows about these supplies that could shed some light on what I could check? Hoping I did not get a DOA unit, as it has been several months since I bought them and I doubt the ebay seller will do anything about it.
Oh, and I've tried using different value resistors, as I've read there are some of the DPS-1200's out there that required something other than 1k ohm. I've tried 65ohm up to 1.2k. Same behavior with all. Also, when it does power up for a short while, the green light is very dim, where as my other unit the light is good and bright.

Any tips?