Just had my Fenix 8 47mm Amoled replaced under warranty and it had firmware 10.x out of the box. Connected to phone then plugged it into my PC to upgrade to 12.35 and on starting the upgrade the screen was as in the first pic.
Once install was complete would get the watch face but then when pressing the buttons the screen would go crazy as in the second pic. What was strange was my phone and Garmin Express both saw the watch as a 51mm amoled. Tried upgrading to a beta version and then manually downgraded back to 12.35 but still the same. Also tried removing maps but no joy.
Spoke to someone in support who said there was an update to cure this but no time line could be given, or have the watch replaced. As the watch is unusable I chose option two. Don’t know if anyone has seen this and if there is a fix so I don’t have to send the watch back. 
