First you need to change the bootloader to SPL1010064 after that you can revert back to any wm2003se rom you like. I dont know where to download rom's but i can give you instruction how to do it.
Go to the folder where you extracted files from TyphoonNBFTools_0.3_SPL1010064_SPVServices.zip and run TyphoonNBFTools.exe
In menu select File > Open NBF... and load SPL1010064.nbf.
Right click on SPL1010064.nbf and select 'Emergency Flash' in popup menu.
Your phone will probably ask a permission to run TyphoonNBFTools.dll. Press OK.
Press OK untill flashing started.
When flashing is done disable USB connections in ActiveSync Connection Settings.
Reboot your phone (turn it off and on). It will run into bootloader.
Run mtty1.42.exe, choose [USB], press Enter and you will see a prompt.
Type "format BINFS" without quotes and press Enter.
When format is finished reboot your phone again. It will run into bootloader.
Run official update and follow the instructions. Wait untill it is finished.
Remember this can brick your device if you dont do it right.
Holux GR-236 Bluetooth GPS