usually on most manufacturers theres a key combination on the remote to "unlock" them (which is usually very obscure and nearly impossible to "guess"). But as for what it is.
- its model specific
- I have no clue where to get em
they put these in because some dvd players are shipped to different regions and they dont always know where they are going to be shipped upon manufacturing. So instead of having to open them up they just have a code to reset/change them.
Like i said i have NO clue where to get em (like i watch any movies outside of region 1 anyways)