The direct ROM patching method for O2 XDA Mini helps eliminate the EXT_ROM to NULL and recovers almost 27MB extra for Storage!!..This is a highly recommended Method. But please be aware that you may void the warranty if you resort to this method. Just follow the below mentioned steps.
1) use romupdate.exe to dump the ROM to the SD card
2/ place the SD in a external card reader, and use ntrw.exe to dump the ROM image in the SD to your PC (ie. execute the “ntrw read filename.nb1 x:” command in your PC, where filename.nb1 would be the ROM image file, and x is your SD card reader drive)
3/ use Hex Editor to open the filename.nb1 in your PC
4/ use the FIND function to locate “02 00 00 80 00 20 20 00 00″ and change it to “02 00 00 b8 01 20 20 00 00″
5/ save the file as “filename_new.nb1″ and execute “ntrw write filename_new.nb1 x:”
6/ put the SD card back to your PPC, start bootloader mode… wait… press Power button…. wait… 100% flashed with checksum error …. soft reset …. wait for several minute at BootSplashscreen…. done!