I formatted my 3DS XL and now it wont turn on.

Hey guys, my problem has me worried.... my game was getting a bit slow so i decided to format it, its a nintendo 3ds XL it took me half hour to fully format the game, then both screens became black and it stayed like that for 20 minutes.... i turned it off and when i powered it back on it was still on the black screen..... HOW CAN I FIX THIS????? HELP NEEDED