Where I can buy this 53p ZIF connector?

Take it from me, I've tried replacing these ports on a couple other 3DS XL PCBs. It's almost impossible without a heating table, similar to the work you'd do to reball a PS3, PS4, Xbox 1 or Xbox 360. The pins are too tiny and almost impossible to heat back up properly.

My suggestion is to just buy a new board. If this is a project or you're attempting to fix and sell back on eBay then "scrap" it for parts.

If you want to experiment and you have a heat gun, you could try heating the part off the board to see if that works. You'd also need some kapton tape to protect other devices on the board while this particular port is removed. If you don't want to damage this board, then look for a cheap "for parts" PCB off eBay that you can practice with in order to heat it up and remove the part.

Good luck if you attempt to fix it. I'd highly recommend replacing the board entirely though.