Something similar happened to me!
I've been checking for the 4.3 update on my phone since the announcement that 4.3 update has started. And suddenly yesterday morning I got the message that updates are not available, because my device is custom. Happened overnight, I've only done OTA updates, nothing else and I've had this update for a few weeks at least (maybe even a month), the baseband for the moment is XXUDMH6.
Do you think that it is possible for me to get it back to official in a similar way - flash the same or a newer version, a factory reset and voila?
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