(See bottom for possible info on repairing an original DS.)
You may email me directly at my user name at gmail dot com--I would recommend this over using PMs.
NB: Read carefully: my text and the comments probably address all the issues you're likely to run into. Also, consider reading my original repair guide on the NDS (affectionately called the DS phat), as well as the comments on both Instructables.
Spend the extra time going over these instructions carefully: why jeopardize several hundreds of dollars in electronics with hasty skimming?
These instructions address how to:
-Replace the touch screen*
-Replace the bottom LCD screen*
-Replace the top LCD screen
-Replace the shell/hinges
Of a DS lite
(* denotes partial instructions: I didn't actually replace these, but I tell you how you'd go about doing so.)
-Jeweler's screwdriver (Philip's head/cross-head as well as flat-head)
-Pliers, if you are replacing the top screen and/or the shell
-Soldering iron, if you intend on replacing the top screen
-De-soldering wick or pump (useful if you're replacing the top screen, but not entirely necessary)
-A needle or hobby knife might be useful in prying off some of the rubber screw-covers
-Double sided tape might come in handy with replacing any of the screens.
You will be manipulating very small screws and delicate wires, and a soldering iron so make sure you are aware of what you're getting into. (i.e. If you have trouble plugging in the toaster in the morning, you may wish to reconsider this repair.)
Where to buy these components & tools:
-The top, bottom and touch screens will be cheapest on EBay. They will likely be shipped from Hong Kong, so it'll take two or three days longer, but it'll be a whole lot cheaper in the long run.
-Shell replacement kits are pretty common on EBay as well
**Note! If you want to swap the colors of your shell, be aware that the frame around the touch screen is part of the touch screen and will remain the same color, regardless of shell kit. (See photo.)
-Triwing screwdrivers themselves are not especially expensive, but you will probably have to look around in shops nearby, or scour EBay to find one that's reasonably priced--shipping charges are usually ridiculous. (Some sellers might include one in a shell replacement kit, so keep that in mind.)
Don't get too caught up in trying to purchase all these items from the same EBay retailer: buying all these items from the same retailer would have cost more, even considering the combined shipping discounts. Do some price comparison!
If you need help replacing the top screen on an original DS, refer to this set of instructions. If you are trying to repair the bottom LCD or touch screen on an original DS, those instructions won't help much, but I'm not too sure how much the DS lite instructions coincide with the original DS's.
Step 1: Opening up the bottom shell
Remove the battery cover and take the battery out. There will now be a tri-wing screw in the bottom-right corner of the console (previously covered by the battery lid), as well as another two at the top-left and bottom-left corners. These are marked by black rings in the photo Unscrew these, and place them aside.
Helpful trick: grab a piece of paper, cardboard, index card, etc. and some tape. As each screw, pad and whatever little pieces come off the DS, tape it to the paper, and label it to help you remember where it came from (so you can put it back later!)
(Note: the photo is pulled from my other DS repair, so those aren't NDSL parts.)
Additionally: you may wish to work on a piece of plywood, plexiglass, or some other stiff, but portable surface. This will allow you to move your mess around without disturbing the components (but if you have a dedicated workspace, this probably isn't a concern.)
There are two rubber feet at the top of the console. Remove these to expose the Philip's head screws. You may find it easier to remove the rubber pads with a needle or hobby knife, but a small flat-head screwdriver works too. There is a third screw hiding in the Slot 1 bay, between the two that were covered by the rubber feet.
Spin the console around so that you are looking at Slot 1 (the hinge side of the console). Stick a flat-head screwdriver into the seam (see photo), and gently pry up.
The two shoulder buttons will become a royal pain if you don't remove them now. Take careful note of how the button, spring and hinge-pin are oriented for both sides before removing them. You may wish to wrap a bit of tape around each set of button-components, since they are prone to coming apart and getting lost.
The exposed PCB is held down by one screw, neatly circled in white on the board itself. Remove this.