First Part : You Have to flash an old firmware using odin of any region to your B5512
Link for Old Firmware- Click Here and download the oldest firmware of THR region (Buid date-03/05/2012) after downloading u will get one xxx.tar.md5 which contains three files (PDA,CSC AND MODEM) u have to split it into three using splitfus2 tool and then you can flash using odin after entering into download mode.
Second Part : Install Kies and update it to the latest version and then connect your device to pc via usb kies will detect your device if usb drivers are installed properly, keep your internet connection on and kies will show your device current version which you have flashed using odin and below that it will show that update is available click on update and kies will download a latest update of your region and install it to your device.
You can check the firmware region by dialing *#1234#
Suppose if you are using firmware of any other region kies will update it to the latest firmware of your region automatically.
Suppose if you are using firmware of any other region kies will update it to the latest firmware of your region automatically.
