Thread: Trying to unbrick a zumo 220

@kunix
Yes, much as i thought. Just one point though, SF posted this:

Originally Posted by smokefree

........
2. I then dump rgn14 as described and compare it in a hex editor to the packed fw_all.bin file. Correct?

That's what i meant is pointless because the packed file will always differ when compared to the dumped 14. It seems logical to me only by comparing 14 to the original [or unpacked] fw_all can there be a valid comparison. So in essence, whether the flash was done with original or packed fw_all, the compare of the dumped 14 has to be to the full [not packed] fw_all, is that right?.

@both
I'd have thought there should be no difference other that the empty padding at the end of the 14 dump. In a 265W i've removed the extraneous FFs and the fw_all and 14 bins are then identical in hex and hash check. Why should a zumo 220 be different? A fault?

smokefree, you've compared the original fw_all.bin and a GarminCure3-ed fw_all.bin. GarminCure3's patch is a bit different from that boot.bin patch.
Looks like the experiment was not 100% clean. Maybe it's a bad flash block which was "frozen" with GarminCure3-ed fw_all.bin piece. Or maybe it's your mistake.

Can you make fw_all.bin full of 0x3E bytes with the size of the dumped 14.bin. Then flash it, then dump it, and compare the flashed one and the dumped one?
It's not dangerous to flash garbage instead of fw_all.bin, you can always flash something else in pre-boot mode after.

Originally Posted by Neil

That's what i meant is pointless because the packed file will always differ when compared to the dumped 14. It seems logical to me only by comparing 14 to the original [or unpacked] fw_all can there be a valid comparison. So in essence, whether the flash was done with original or packed fw_all, the compare of the dumped 14 has to be to the full [not packed] fw_all, is that right?.

Right.

Originally Posted by Neil

@both
I'd have thought there should be no difference other that the empty padding at the end of the 14 dump. In a 265W i've removed the extraneous FFs and the fw_all and 14 bins are then identical in hex and hash check. Why should a zumo 220 be different? A fault?

Yes, when the experiment is 100% clean, this would indicate a fault. We can overcome such faults if they are not too abundant.

Originally Posted by kunix

Can you make fw_all.bin full of 0x3E bytes with the size of the dumped 14.bin. Then flash it, then dump it <...>

New territory for me here. Could your request be translated as: "Replace the contents of the dumped 14.bin by 0x3E bytes, then flash it, then dump it <...>"?


Edit:
Have opened a copy of 14.bin in a hex editor. I did find the option to replace a string by another string, but have no clue as to how to replace the entire contents of the file with 0x3E bytes.