I checked the service manual for any type of un-lock code for this unit and could not find any. You may want to try a diiferent route to be able to watch any region DVD's on your DVD player.
You can get a software that will let you copy any DVD from any region and with any type of copy protection and it will make the copy into a high quality region free DVD. You need a DVD burner on your computer and some disc copy software. Any copy software will work with this software that works in the background of your computer on the DVD drive. It strips away region codes and copy protection and then your copy software will copy DVD's that it would normally tell you it can't because of copy protection. They also sell copy software that works great also, but it is not vital to have that.
You can get a free trial of the software for 21 days here:
The software I am referring to is the first one on the page. The copy software is the one right below the HD version. I have been using this software for years and it is by far the best you can get for these type of problems. Then you never need to worry about what type of DVD player you are using in your car or your home. You will have region free DVD's from any region you get them from.
Let me know if I can be of any more help.