Its menu navigation is slow and it is crashing out to Android home.
When it boots, it should boot straight into Kodi (and ideally, recover into Kodi after a crash).
I get you may have your heart set on a new box (and may even have it by now) but, by sounds of it, you're running Kodi via Android, not on LibreElec? If so, just saying, the difference in speed of menu navigation and stability (crashing) was night and day when I switched from Android to LibreElec on my S805 box. Might be able to get some more mileage out of your S905.
Kszaq used to publish images for these boxes but seems to have moved away from development. CoreElec appears to be picking up the gauntlet. You can run off SD card too if you want to keep your Android OS available.