You may need to use WPInternals to "unlock the bootloader" before flashing, or the emmc itself may be physically dead. 5. Where to Find Reliable Emergency Files (Repack)
Because official Microsoft servers often lack these specific files for the Lumia 650, you may need to source them from community repositories: Lumia Emergency Files Archive : A third-party collection of emergency packages. LumiaFirmware Alternative : A community-maintained database for RM-specific firmware. 4PDA Lumia 650 Thread
For the Lumia 650 repack, the command might look like this: