Complete Solution - includes fix for Bluetooth.
You will need to execute a number of steps to do this:
1 - obtain a copy of the latest firmware from http://www.samsung.com/uk/support/search/supportSearchResultView.do?group=&group_cd=&type=&type_cd=&subtype=mp3others&subtype_cd=&model_nm=YP-T9&dType=D&vType=L&mType=&model_cd=&menu=download&prd_ia_cd=&disp_nm=YP-T9
or (even better) - go to the international site and download a copy of YP-T9 V1.80.zip
2 - Reset - Power off the yp-t9 using A-B and MENU pressed together - hold down A-B and press the POWER button to enter the low-level format mode - press LEFT LEFT RIGHT RIGHT UP CENTRE DOWN - the yp-t9 will now reformat - power off using A-B and MENU together
3 - reload firmware - Power on normally and connect to PC as a USB drive. Move the two files you just downloaded (MUON.ROM and SYSDATA.BIN) into the root of the USB drive - Safely remove the drive - Power on the yp-t9 and allow it to re-install the firmware
If you want to restore Bluetooth functionality you will also need to perform the following steps:
4 - pop the four rubber plugs out of the back of the unit - with a small phillips screwdriver remove the four screws - insert your fingernail into the seam of the unit on both sides and pop off the back - gently (slowly) remove the battery taking care not to place any strain on the connecting wires - copy dowm the 12-digit number on the label under the battery (starts 0016xxx...) - replace battery, back, screws and plugs.
5 - using text editor create a file with the 12 digits (use upper-case letters where appropriate) followed by <enter> key - save it as BT_MAC_ADDR.TXT
6 - connect the yp-t9 and open it using Right click on Start and Explore - find the yp-t9 and drag a copy of BT_MAC_ADDR.TXT into the SYSTEM folder - Safely remove - power on normally.
Hope this helps