6i25 Error: BootSector is invalid

$ sudo mesaflash --device 5i25 --readhmid
ERROR: no HOSTMOT2 firmware found. FFFFFFFF
Configuration Name:

General configuration information:

  BoardName :
  FPGA Size: 0 KGates
  FPGA Pins: 0
  Number of IO Ports: 0
  Width of one I/O port: 0
  Clock Low frequency: 0.0000 MHz
  Clock High frequency: 0.0000 MHz
  IDROM Type: 0
  Instance Stride 0: 0
  Instance Stride 1: 0
  Register Stride 0: 0
  Register Stride 1: 0

Modules in configuration:

Configuration pin-out:

 sudo mesaflash --device 5i25 --fallback --write 5i25_7i85sx2.bit
Checking file... OK
  File type: BIT file
Error: BootSector is invalid

$ sudo mesaflash --device 5i25 --fix-boot-block --write 5i25_7i85sx2.bit
Checking file... OK
  File type: BIT file
Erasing sector 0 for boot block

$ sudo mesaflash --device 5i25 --fix-boot-block --fallback --write 5i25_fallback.bit