PB 622 - Problem - blank screen during downgrade

[Kartka]

Hello, I've got a problem. I've decided to downgrade firmware to 3.2 (there was USB connection problem with the latest firmware). I was doing this like they said in the manual, put microSD card in, there was 'firmware update' message on the screen and command to push context menu button so I did it and then screen went blank. There is no instructions, what to do next. Only diode shines. I'm worried, is this ok? When I was updating firmware some time ago, there wasn't any problems.