I was wondering, could this behavior be caused by not having a TAA board? I just read about it but I'm confused. What is the TAA board and what does it look like?

Thanks

TAA  refers to Trade Agreements Act - it's a module designed to allow Dell (or whoever implements it) to track goods that are or are not allowed for sale in certain circumstances (such as to governments that are or aren't signatories to the Act).

The E4310 is built both with and without the TAA socket - but if there is a socket,  you must install a TAA module in order to user the system.

If you look at the photo in the link below, you'll see the TAA socket (it's the open white socket in the board).  If it's there and there's no module, you'll need to purchase one for the system (or exchange for a non-TAA board).

www.parts-people.com/index.php?action=item&id=13587

Have you tried more than one AC adapter?  Are these Dell AC adapters, or third party adapters?

Ok, I have some more information. The motherboard I'm testing does NOT have a TAA connector so that's not the problem.

I noticed something I hadn't noticed before. If I plug the power source BUT DON'T PUSH THE POWER BUTTON, the three leds light up. The leftmost one starts blinking, the other two remain solid blue. I checked online and it appears that the one blinking is the HDD, while the other two are battery and wifi (picture below). But what I thought was most strange was that the CPU was getting hot. Again, this is just plugging it to the power source without actually powering up the system. The fan remains off, it only starts spinning if I push the power button

Thanks

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Ok, I think I made some progress today (but not quite there yet). The hint came from the comment in my previous post that simply connecting the power supply I'd get the LEDs go on and the CPU get hot. It turns out that doing that would start the computer but the CPU fan didn't start spinning because it wasn't hot enough. Then when I pressed the power button I was actually turning it off, not on, and in the shutdown process the CPU fan spins for a few seconds. To make things worse I was looking at the wrong monitor. I had one connected to the DVI port and another one to the VGA (I was looking at the DVI but the display was being sent to the VGA). So anyway, what I get now is the following. I plug the power source, all three LEDs illuminate, the monitor shows the DELL logo with the blue progress bar and a yellow message at the top right side of the monitor says "DIAGNOSTICS BOOT SELECTED". Then, once the blue bar fills up (takes one or two seconds), the screen goes black and nothing else happens. The LEDs are still on. If I connect a hard drive I can hear the HD spinning all the time from the moment I connect power. After a while the CPU fan starts to spin as well. I've left it running for 10 or 15 minutes but nothing else seems to be happening. I tried swapping two 2Gb RAM modules that I have, I also tried using one module and placing it in either slot. Still no luck. Any ideas? What is this diagnostic boot mode and how can I switch to normal boot (maybe it's something it does the first time?)?

Thanks for any help