DSi troubleshooting, can't even access menu, help

I’ve had this problem for a while but I haven’t done anything about it.

Anyways, whenever I turn on my DSi, I get a black screen that says “An error has occurred. Press and hold the Power Button to turn the system off. Please see the Nintendo DSi Operations Manual for help troubleshooting.”

I know some people have had a similar problem, and that they can’t open any app, but the thing is I can’t even access the menu, everytime I turn it on, like 2 seconds after I do I get this message.

What should I do?