Thread: Trying to unbrick a zumo 220

Originally Posted by smokefree

OK, but from post #1 (Edit 2) we know that the zumo does not read from the microSD voluntarily. I needed to perform the trick Neil described in post #4. Would that be the same procedure for this 0x3E version of 14.bin file?

That trick is used for running update.txt files when fw_all.bin crashes.
So you should run update.txt using that trick. And update.txt should contain command xrgn,14,1:/14.bin.
And SD:/14.bin should contain the required amount of 0x3E bytes.

Result as follows:

1. Flashed 0x3E version of 14.bin into the zumo as described.
2. Flash operation completed successfully.

Code:

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3. Zumo indicates "SYSTEM SOFTWARE MISSING".



4. Dumped rgn14 successfully.
5. Compared the dumped version of rgn14 to the flashed version. Both are identical.



6. Edited the two bytes of the original 14.bin to be identical to the pristine fw_all.bin file (except for the FF's at the end).
7. Flashed the resulting 14.bin file into the zumo.
8. The flash completed successfully, but when on USB cable to the PC (or when on wall adapter power), the unit now goes into a continuous reboot every 7 seconds, briefly showing a fully white screen before each reboot. This is the same symptom as when flashing ORIGINAL FW into the unit using GarminCure3 and Updater.exe.

Any other suggestions?

Are you sure that when dumping 14.bin you've deleted the previous 14.bin and that rrgn,14,1:/14.bin has completed successfully?
If it is so, then I don't have any other clues. We've cleaned NV and formatted the internal flash drive region 48. Region 14 seems to be okay.
So it should have started working already.

A good idea would be to find where it crashes/reboots. It would require dumping the crash log region, or even creating our own crash log handler and writing data manually to the crash log region.
It's a lot of work to do, I don't have enough time now.

Originally Posted by kunix

Are you sure that when dumping 14.bin you've deleted the previous 14.bin and that rrgn,14,1:/14.bin has completed successfully?

Deleted from where? Yes, I deleted the previously dumped 14.bin from the microSD before flashing the 0x3E version of 14.bin.
Also yes, I deleted the 0x3E version from the microSD after flashing it and before dumping 14.bin again.
However, no, I did not delete (erase) rgn14 from the zumo before flashing the 0x3E version of 14.bin.

I can confirm the command rrgn,14,1:/14.bin has completed successfully, based on the contents of updater.log.

Originally Posted by kunix

A good idea would be to find where it crashes/reboots. It would require dumping the crash log region, or even creating our own crash log handler and writing data manually to the crash log region.
It's a lot of work to do, I don't have enough time now.

First of all, I appreciate all the help and patience received so far. Just the fact you would be prepared to assist me with the crash log is also much appreciated. The least I can do in return is have the patience until you have time to assist. Do you have an indication when you could do that? I can then inform my friend. The zumo is no use to him in this condition anyway.

Originally Posted by smokefree

Deleted from where? Yes, I deleted the previously dumped 14.bin from the microSD before flashing the 0x3E version of 14.bin.
Also yes, I deleted the 0x3E version from the microSD after flashing it and before dumping 14.bin again.
However, no, I did not delete (erase) rgn14 from the zumo before flashing the 0x3E version of 14.bin.

I can confirm the command rrgn,14,1:/14.bin has completed successfully, based on the contents of updater.log.

Okay, good. Or better say, not good, because you've done everything correctly and I have no more clues for real.

Originally Posted by smokefree

First of all, I appreciate all the help and patience received so far. Just the fact you would be prepared to assist me with the crash log is also much appreciated. The least I can do in return is have the patience until you have time to assist. Do you have an indication when you could do that? I can then inform my friend. The zumo is no use to him in this condition anyway.

Let's say, in the first weeks of december I will be able to investigate this for sure.

No problem, kunix. The zumo will still be here. Thank you!

I have the same sentiments as described above by Neil. When I joined this forum 4 years ago, I was a total rookie. Apart from being a Garmin GPS user, I had no knowledge of what went on inside the unit. Ever since then, my knowledge has experienced a steep learning curve which still continues today. I feel like a sponge, soaking up knowledge, and which still has a long way to go before even getting near its saturation point. There is just so much to it...

I appreciate all the help and advice I get here and realize things sometimes need to be spelled out to me. Partially it is due to my limited knowledge on the topic at hand, but also to avoid a wrong assumption and making things worse. This project will no doubt be of great interest to other readers too, either now or in the future, which is why I make it a point in describing my actions as clearly as possible. At some point in time, others may benefit from it.

"Giving up" does not apear in my vocabulary and my aim is to persevere until either the goal has been reached, or there is no other reasonable conclusion than considering the goal not feasible. Thank you to kunix and Neil for helping me so far. Looking forward to continuing in December. In the mean time I will perform all steps again to double check I did things right and will post back if necessary.

It is with regret that I have to inform all who were watching (and participating in) this thread that my friend has decided to sell the zumo 220 for parts. As of today I therefore no longer have the unit available.