Since you did not provide any details of your custom drums / pack, we can hardly speculate what exactly caused your problem. Yamaha does not publish error codes of Genos, and we do not have access to the source code of the Linux operating system of Genos (firmware 1.10), none of us have any clue on the "omlszrjboo L349" error.
I recommend you go through the following process for debugging:
1. Narrow the scope of your problem by divide and conquer / process of elimination - to identify which custom drums / custom pack caused this unexpected error.
2. Contact Yamaha customer support to report such error to open a support case.
3. Provide your custom drums / custom pack to Yamaha customer support for the support engineers to reproduce the error.
4. Follow up with Yamaha customer support for a resolution.
Your Genos reseller probably had no idea of what your problem was and so recommended you to reset the entire package. I doubt if the reseller qualifies for providing this kind of custom support for your specific usage issue on Genos.
Your issue could be just incompatible voices between Genos (SWP70 tone generator) and Tyros 5 (SWP51L tone generator), which can be resolve by remapping the Tyros 5 drums voices to appropriate Genos drums voices to create a new custom pack based on Genos native voices.
Since YEM 2.5 did not complain about your custom pack and Genos loaded it successfully, and you encountered this unexpected error while using this custom pack, this "unexpected error" could be an indicator of a defective Genos unit, which could happen in early production cycle of a new product. That is why you should involve Yamaha customer support for a solution / repair / exchange, since you should still have valid warranty to cover such situation.
If you want to see whether your custom drums / pack causes the same unexpected error on other Genos or not, you can first identify the offending custom drums / pack, then upload that pack to somewhere like Google Drive, or similar online storage sites, provide a link to us so we can download it and process the pack with YEM 2.5, and install it on our Genos. If we also see your problem, then it is a voice related issue, or could be data corruption issue. If your custom drums / pack works fine on our Genos, then you more likely have a hardware issue on your Genos.
Thanks and good luck,
Paul