What I read is that I could install Garmin Express on my windows machine, then connect via a USB cable and there would be a menu of versions I could install.
Another option is to make sure Garmin Connect on my android phone is properly paired with the new device and then the update may just happen via "osmosis".
I go to Main menu -- Setup -- About.
(About is at the very bottom)
It shows me that I have Software version 9.50.
The latest version is 10.20 according to this page:
Now I launch "Connect" on my phone. At the bottom right I see "More". Inside More I see "Garmin Devices". In there I see my Instinct and my old66i. At the bottom is a big blue button "Add Device"
After a few seconds I discovers my 66i and the 66i launches a "Pair phone" screen. I click on the button at the bottom and then again on a subsequent screen. I get several more screens (Android gets involved with permissions), but I just rattle through the screens.
Garmin connect now wants to sync, but reports "something went wrong".
Aha! I need to turn bluetooth on in the 66i inside Setup.
Now the Connect App shows the 66i in the list of devices and shows it as connected.
Apparently there is no way to push an update from Connect to the 66i like I would like, but I'll leave them in proximity and powered on for a few hours and see if magic happens. They make some statement that the purpose of Connect is to sync activity data from the device to your garmin account with fitness goals in mind, but "it also allows for software updates".
After a few minutes I decide to cycle power on the 66i. It still reports a pending update, but maybe with my phone close it will do it. Aha! Garmin connect shows a progress bar labeled "sending software update". I'll wait for that to finish and see what happens. The 66i is just sitting there showing me a map. The progress bar is taking quite a long time, and now seems to have started over (or a second update is following the first??) The second "update" finished quickly and now the screen on the connect app seems quiet, just saying "Connected". I'll give it a few minutes then power off/on the 66i.
After 5 minutes I power off/on. I get the usual question asking about installing the update. I say yes and it finishes in about 5 seconds and shows me a map. It is still running 9.5.
No magic yet. I'll leave the phone and 66i side by side longer, maybe overnight, and see what takes place.
The next thing to try is installing Garmin Express and then trying to do the update via a USB cable.
Now the big test, we power it off and back on. Voila! It works. No more asking me about installing new software on every boot.
Tom's backpacking pages / tom@mmto.org