trying to reverse engineer the mig switch

[ssarfaty]

as found in the board projects here: https://github.com/sabogalc/MIG-Flash-PCBs/tree/main/Boardview%20Files

it seems that the mig flash dumper is using ice40.
i have taken the firmware that need to be uploaded to the migflash and migdumper from the website: https://migflash.com/

then when trying to run iceunpack i got this:
iceunpack update.s2
Error: Unexpected end of file.