Courtesy of pepar, here is the procedure to check what you've got
1. With no disc in the player, drawer closed, turn the main power OFF with the "On/Off" button.
2. Press and hold the Play and Open/Close buttons at the same time.
3. While holding the buttons in 2 above, turn the main power ONwith the "On/Off" button and release the two buttons after THREE SECONDS.
4. The Play/Pause indicator in the lower left portion of the display should appear.
5. Wait for the Loading message to clear from the display.
6. On the remote control, press the numeric buttons "3" "2" "6" "5"
7. Press the menu button on the remote control repeatedly until you have checked that the four version numbers . . . have shown in the display.
8. To reset the player, turn the Main power OFF with the "On/Off" button.
Regarding what is the latest fw, I was told that depending your hw build the site will suggest the latest fw applicable