Alright, here's the deal.
A friend gave me his old Latitude CPi, complete with basically everything but the battery. He said that he didn't need it anymore, and that it worked fine except that the adapter was broken. I think someone stepped on it and the piece that connects into the computer broke.

So, I thought, "Hey, no big deal, replacement adapters are on eBay for like 15 bucks."
So I bought one and tried it out. (It has been double-checked, it IS compatible with this computer)
The adapter itself seems to work fine, as the green light on it will be on if it's plugged into the wall. However, there is no recognition by the laptop that it is receiving current. No lights on the laptop anywhere. When I press the on button, nothing happens. Absolutely nothing...

My boyfriend and I painstakingly took apart the computer today to make sure there was nothing obviously fixable. The on button seems to work fine, and I didn't notice any incriminating evidence of overheating or anything like that.

This brought me to think, "Maybe I just need a battery in the slot." However, the friend that gave me the laptop said he never had one in there, and I believe I heard the computer can work directly from the adapter.

What do you guys think? This is very frustrating, as I do not have money to purchase a new computer and I was going to use this one for my artwork since people are constantly on the two available computers in this house... *sigh*

The battery is not required (although it must be used near a power outlet only of course )

If you take the 6 long keyboard screws back out, and then unclip the keyboard from the palm rest (but leave the data cable it plugged in)
Push gently but firmly down on the daughter board that connects directly on to the Motherboard (this board is also screwed in, but can become loose)

Try powering up again

If it still doesn't work you may need to either push a bit harder, or remove the entire palm rest and refit the daughter board (Note: I call it the daughter board but it's probably called something else)

Okay, well, we ended up taking it mostly apart and the "daughter" board was stuck somewhere, so we didn't get it totally out. However we figured it would be fine to just stick it back into its plugs and see if that worked.

When we plugged the adapter into the computer, there was a spark somewhere on the board. A closer inspection revealed that there was a chip that had been burned... T_T I'm not sure if that just happened, but I doubt it given the circumstances. I'm kinda curious as to how that happened if it WASN'T me, but like I said before, the previous adapter was broken, so there might've been a power surge when someone tried to use it...

Thanks for your help, anyway..

I think it was you.

And that "daughter" board does get stuck, that's correct, you just need to pull it a bit harder (screws out first of course)

But now it went spark, um, it might not work again

Yeah, we were just afraid of breaking it, lol.
Oh well.. spare parts for me.
BTW, what are those boards officially called? People sell them, don't they?
(Not that I'm seriously considering buying anything else, I'm just curious on how much it would be to replace)

Hi, just throw that laptop and forget it, if it had spark and it was fried, then u dont waste you precious time on it.

Now I did know But can't remember

Just check the board for any markings like numbers or stamps or something
Then look that up
Mind you, battery doesn't work
300 MHz
..
Just sell faulty on eBay

Oh, something I just realized!
The first time we took the keyboard off, we noticed it REALLY smelled like burnt electronics. I figured it was normal since I don't have a lot of experience with computers, and I thought it was probably just because it got overheated or something.

However now that I think about it, that smell is only coming from the burnt chip area, which means it's pretty likely the thing was DOA, lol. I feel stupid for not realizing that sooner..

Oh the underneath of the keyboard touched the electronics
Actually this may prove that "daughter" board was slightly raised

That's it
Oh and under the keyboard you may see a black darkened area (the flash burnt area)

Yep, you're right, I noticed that when we first took the keyboard off and wondered if it was normal. It lines up perfectly with the chip..

I wonder how that could've happened.
I think someone had been inside the computer before us though, because there was dog hair in it o_o;
Maybe they were careless with the daughter board. lol

Solved

Well you still need a new daughter board and all

But "Dell Latitude CPi D300XT refuses to turn on"
That's because it's burnt out.

Now can you throw it away

The computer or the board? XD