You don't see PIN, you see password screen from where 2 company.
Difference: PIN is 4 number and password is 6 number.
Try, you will see that you need 6 number to enter.
This password have only Where2 company and you can't remove it.
I also have in hand 2495 from where2 and try all that i can think, but this password always stay.
If you search for specification you will see that nuvi 2495 don't have PIN function, but this device have OEM firmware and this is reason why you see password screen, becouse this FW is created specific for Where2 company.
This firmware also don't alow to store gupdate.gcd on unit, when you try to flash unit with regular FW, you automatic start protection on device and now you see password screen.
Only thing that you can do is, to send back to seller this unit or go to Where2 company and maybe they will tell you password for unlock device.