Some of the problems when repairing the Nintendo DS Lite can be simple and cheap, such as a fuse problem or expensive water damaged problem. Hopefully this will give you some understanding of diagnosing and fixing Nintendo DS Lite.
I got a batch or NDSL to repair - all do not power up and turn on at all. Here are the common faults. Any new scenarios I come across I will post it here, or if you have one that I havnt come across yet - let me know.
Simple Fuse replacement
Check the fuse and solder new fuse in. Usual symptoms are no power but charge light on when plugged to power.
Fuse and Dry Joint, loose components
In this case the fuse was OK. Seems like the NDSL was also dropped with a SMD component floating around causing it not to power up. Solder SMD component that fell off back on and it worked.
Blown Fuse and Faulty/burnt TOP screen ribbon cable
In this case, the fuses were blown and when the NDSL tried to power up it the bottom screen flashed white and went off after replacing the Fuses. On closer inspection the top screen ribbon cable was damaged due to fuse and NDSL shorting. This can be repaired but the silver resin cost more then the screen.
Replacing the top screen requires you to also desolder the speaker and resolder it onto the new screen, which is fairly easy to do. ( This is done for DS Lites that are in two pieces - you would also need to replace Mic and wireless antenna. )
Water Damage Nintendo DS Lite ( expensive repair )
Water damaged NDSL can be hit and miss. I have repaired some with obvious signs of water damaged but only the fuse was blown and it worked.
This one pictured here is very expensive repair - not worth repairing really - but it depends on what can be salvaged. The board is rusted and seems like it was in water for a very long time. ( didnt notice when I bid on it on Ebay - so beware )
To get this up and running you will need to replace the Motherboard, Both screens and while your at it replace the touch screen aslo. Only thing that could be salvagable is the shell, speaker, mic and wireless antenna.
Water Damage Nintendo DS Lite ( Repairable )
Bought this off Ebay for $29.95 delivered ( was put in a washing machine ) and found out that the motherboard was still good but Both screen were dead. Total parts to repair was around $30. If the motherboard is bad then it isnt really worth fixing, so its a gamble. Not all of the time though the waterdamage one above wasnt worth getting.
Below, you can clean it with isopropyl alcohol and a cotton bud. You can also scap the corrosion with a scaple.
Picture or burnt ribbon cable.
Another scenario - Burnt out motherboard ( expensive repair )
In this case, It doesnt smell burnt but looks fried. Most likely cause would be 240v power/110v supply attached to NDSL plugged into wrong power voltage. Screens were OK, but when I placed a spare motherboard on there is a constant high pitched buzzzz.....annoying - thought it was speakers and replace it - buzz still there, I suspect that its the bottom LCD Screen.
Re-Sit Wireless (very easy - simple scenario that I came across )
"IT STOPPED WORKING, CHARGING LIGHT COMES,POWER LIGHT COMES ON, BUT NOTHING ON THE SCREENS"
I got this one working by resitting the wireless, This NDSL I got about AUD$60 AUD delivered. When it powers on theres Green lite but no screen, charge light is fine. When I opened it, the fuses were OK, just noticed the Wireless bit wasnt as firm, re-sit it and then tested it. Then the unit powered on and works fine.
Faulty Case / Cracked Hinge
"NINTENDO DS LITE ** BLACK** FAULTY TOP SCREEN DOES NOT WORKTOP RIGHT HAND HINGE BROKEN, CAN PLAY GAMES ON BOTTOM SCREEN, GOOD FOR PARTS OR SOMEONE THAT KNOWS HOW TO FIX IT,"
Got these for $50AUD each, To get these working again, I needed a new Case and Top screen. It was a easy fix.