Robbie .. since yesterday I'm trying to fix that stupid error.
1) Tried with a mst MD5 checksums ... My tester hasn't a corrupted file.
2) Check the hardware revision. We have the same : 2101
3) I told the testers try to flash with the root image extracted from a fiascoimage.
That flash went fine.

So to two testers everything all right... and two with that error. ... and I do not understand why ..