Flash drive for by pass system for immobiliser?

I lost my key for my Nissan X-Trail ST 2003. I got another key cut but it will only half start the engine. A person who looked at it said he could program the key to the engine but not the iginition box, he said I need a new Nat box. A Nissan dealer said I need a new computer system worth $3500 - $5000. I was told about this flash drive to bypass it all is there such a thing and will it work for me?