Bought my M105 May 2002. Following hack worked:
Cold Start
Ensure tray is closed and no disc inserted
Press Repeat on handset
Enter 57538
02 should appear on the screen
Press 1, 2, 3, 4, 5 or 6 to set the player to the desiered region
Or Press 9 for auto-region (even for RCE discs)
Press Open/Close to open the tray (do all this before 02 disappears)
Wait at least 15 seconds
Press standy/power on the remote
Next time you turn machine on its in the region you set
Got that above from here:
http://www.709firmware.fsnet.co.uk/faq.html
good luck