Help, Please

My DSi shows that I have an extremely low battery (flashing red) all the time, except when it's plugged in. The only time it's in the blue is when I have the charger plugged in, and it goes straight to flashing red as soon as I unplug it, and it shuts down about 10 seconds later. I can't go anywhere with it...For anyone that this has happened to, or has an idea of what is going on, can you please give me some advice? (this even happens when it's "fully charged" according to the little battery symbol). Thank you. :/

Throwback to my cringey emo phase.

What they said

I WARNED YOU ABOUT STAIRS, BRO!

Yeah. Same thing happened to me. xP

I miss you guys so much.

Thanks guys :)
Are the batteries expensive?
And where can you get them? :/

Throwback to my cringey emo phase.

Call Nintendo my dsi got crushed 2 times and I got a brand new 1 with all my data on it and they realy nice too.

Lifes like a game there are those who are good at it and those who need practice.

idk i just keep my light really low and my battery last the entire day.

SSDD

Need a new battery

I'll be back every now and then