DCS 420-Don't know what I'm doing wrong(and opening these up)

Alright, so after putting off my NC2000e until I can give it some more attention, I have bought another from the series-a DCS 420c.

This one came to me with a 160gb hard drive, which I installed for testing.

When I unboxed it, I plugged it in and got the all segments lit/clicking inside that my other does when plugged in, so I took that as a good sign.

Pulling the bottom off showed me some corrosion on the battery pigtail, but i was able to get it out without damaging the connector on the board. Plugging a fresh pigtail in here showed me 14.4v across the terminals, which seemed good(my NC2000e only shows like 7V here).

So, encouraged, I tried connecting an 8x AAA pack I have made up. At first it seemed like everything was working as it should. When I flipped on the power switch on the camera, the hard drive started spinning up, the LEDs flashed on the back, and the LCD started making some sense. That was short lived, though, as very quickly I saw a wisp of smoke come out the bottom so I shut the whole mess down.

I double checked my battery pack wiring, plugged it all in again, and the next thing I knew I had pops and a lot of smoke out the back.

As of now, I get no signs of life whatsoever-no LCD segments or anything else.

When I plug in the wall plug, I get 14V still across the battery terminals(no battery connected). If I connect a bench PSU to the battery pigtail(no power adapter connected) something is drawing ~100mA but I can't see any life from anything.

Totally disconnected from the back, the N90s seemingly works perfectly. At the shutter opens and closes, the camera meters and AFs, etc.

Any idea what could be going on here, and what I might have smoked in this process?

Also, I tried to dig deeper into the mainboard of my NC2000e but got stuck on it. I was able to get the PCMCIA cage out, but it seemed the standoffs for the SCSI port may have been holding it down. Any ideas for those without making a mess(if that is the problem)? The seem deeply recessed enough in the plastic that I wasn't able to get a nut driver on them, or really even just grab them with pliers and turn as I've been known to do before removing them on computer expansion cards.

You will need to take it apart and see where the smoke came, you might be lucky and is a regular of the shelf part.

On many cases the tantalums go short with a lot of smoke and a pop and they remain short so maybe a fuse has blown. I had this exact problem on the DCS100 and it was scary...

As for the SCSI port, yes, you need to take down the standoffs. In mine they were not tight, just using some small tweezers I could remove them.
They don't use really weird parts, you have a high chance of fixing it with a lot of patience.

I managed to get it open and this IC is the only thing obviously smoked I can find

I've managed to hopefully find replacements, so we'll see.

I spent some time probing around other areas. All the fuses I could find are good. I didn't check all the resistors but the ones I did are in spec. I need to check the caps, but nothing looked obviously off and of course there are no big electrolytics to worry about.

I did probe around a few traces that have whitish deposits on them, but all are good that I could find...

Hmm that's a FET, they blow because something else went wrong, if nothing obvious is shorted after that, a shorting tantalum can totally be the culprit.
I can see one quite near the area of failure, Prior removing the dead FET one really easy way to rule out for shorts is to apply voltage to that part of the circuit with a bench supply and see where the heat goes. Using very safe values of course like 1v at 1amp, is quite safe to apply those on the capacitors that are obviously for power supplies.
1V is too low to power anything, even less to damage anything, but well enough to generate heat on any shorted component.
You can apply a freezing spray to check where it heats, or if you have access to a thermal camera that's much better.

The proximity of the inductors makes me think this FET might be part of a PWM DC/DC converter. If so, it could be whatever controller is driving the FET. You'll need to remove the FET first, regardless, and then you can check for a short at its output and maybe try applying power to see what is being fed to the gate.