can you still make USB connection with your PC? If yes, I can prepare you file system backup that you can copy back on your Mio.
..but in other hand you don't even need full backup. You can try with SD unlock script first which I prepare you for your Moov 500:
[Only registered and activated users can see links. ]
copy both folders Cobia_500_64 and Apps on a fat32 formatted SD card and make a reset. Your mio should boot into new shell/menu from where you can launch your favourite navigation (iGO primo for eg.) but off course it has to be installed first. That is the next step so first things first.