I'd say just buy a new 3DS (if you do the XL is way better!)
Because if you do send it in it will cost as much as a new one, except you will probably lose all your save data, streetpass data etc on it, because all repairs like this employs lazy people who don't give a damn about your data.
Buy a new one and do a System Transfer, if your upper screen doesn't work it's fine because all the actions you need to do are on the lower screen I remember.
Yep.







