The battery doesnt charge anymore. Even when it is pugged in the orange light still flashes to say its about to go flat. As soon as you unpulg it, it will die. How do I fix this?

This could be as simple as a battery. Check that with a voltage meter. If you replace it this will probably be fine.

Does the battery hold charge for long?
THe flashing means not charging..
test another power adapter or change battery

popped a fuse...youll need a repairman

The computers contact point for the charging cord is "VERY" sensitive for me. I had to try many times to actually see the charging "icon" light up before letting it charge. Many times the icon would go back to "battery" during charge and I would have to re-try the connection again... Very annoying. If the battery get so drained that you can't see the "charging" icon, then it's a guessing game as to whether it's charging or not. I needed to re-install the OS and it took me 3 days to get my battery charged that way.

If you ran the battery to the point of almost draining it, then the light being orange is from below 25% charge

Your DS is either fully charged or the battery got damaged/wet. When you play the DS, is the light red or flash red? If it does, then the problem is with your battery. http://www.nintendo.com/consumer/repair/dslite_repair_home.jsp
Click on your country, then "System and Game Problems," then "Power and Battery Charging Problems."
Hope this helped.

Batteries lose their capability to charge to their highest capacity after each charge. I would reccomend a new battery.

Your sidekick 3 will NOT charge anymore .
even if the orange light is on & it says charging
it WILL NOT charge . Try using an old sidekick
&just charge the battery on it & then when its
done charging switch the battery back to the other
sk3 .

The battery is flat.
If the battery is very flat sometimes the phone will not start charging or turn on even when a power cable is connected.

This worked for me:
- Remove battery
- Insert power cable/usb cable
- Orange charge light should start flashing
- Re-insert battery
- Leave phone charge for a couple of hours
- Turn on

DO NOT continue to try to charge that battery. The company recalled those batteries because they explode or start on fire. Do a google search of "mintek" and you can read about the recall.