Pocketbook 614 stuck on boot screen

Hi everyone,

Recently I had problems with my pocketbook basic 2 (614): at first it was not responding quite regularly and not starting. So I upgraded to the latest firmware.

But now, at boot, it's stuck on the boot screen with the hourglass...

Any idea?

Actually the ereader is quite easy to open and I found out that the internal memory is just a micro SD card. Does anyone know how to reinstall the OS on the SD card? (and perhaps have a copy).

The partitions on the SD card is a bit strange, there are 5 different partitions...

Thanks!