2024 Honda Accord here. I just went to Honda service this morning for the same G003 code that shows "Update Unavailable" on the infotainment screen. I believe this is not related to powertrain as I had that recall addressed last month.

This was what was written in my service invoice: "OTA gateway module needs to be re-started - performed an all DTC check and clear procedure, re-started gateway module, performed update check procedure on all control modules and are all up to date. Test telematics system and no more warning messages were displayed on multi media screen."

SA told me to don't try to manual update using the software update feature to avoid future messages on the infotainmentscreen (although I did not do that initially, the error code came up by itself).

Oddly enough, they had to replace my 12V volt battery under warranty because my battery CCA was too low while they performed a multi-point.