Flashing a higher OS version via autoloader is easy, but "downgrading" is notoriously difficult and can lead to permanent hardware errors. BlackBerry Infrastructure:
Unlike the consumer-friendly BlackBerry Desktop Software (which requires an active connection and official OS bundles), an autoloader writes directly to the device’s NAND flash memory at the bootloader level (also known as Engineering Boot Mode). blackberry 9800 autoloader
Because this process performs a "factory wipe," all user data is permanently deleted unless a manual backup is performed beforehand. Flashing a higher OS version via autoloader is