I’ve only been a Glass Explorer since January, but the following has worked for me with every firmware update, even within minutes of the Glass Team announcing one, which makes me think that it’s no longer just dumb luck:

1. Be within range of a saved Wi-Fi connection (obviously) with the battery at over 50% already.

2. Turn Glass off by holding down the power button for a few seconds (as opposed to a quick press for Standby Mode).

3. Plug Glass into the charger, which will of course automatically power Glass back on.

4. If it doesn’t update after a few minutes (make sure to give it enough time to download the update in the first place depending on your Wi-Fi speed), unplug Glass from the charger and start over again at Step 2.

I’m not a developer so I’m not 100% sure why this works, but I originally theorized back when I wasn’t getting my first update that Glass probably “checks in” as soon as it finishes booting up just like Android phones & tablets do, and since it needs to be on Wi-Fi and charging with at least a 50% charge to update I figured why not make sure that it had those 2 requirements already met upon “check in” at bootup.

*UPDATE (05/06/2014) - This method is not working for me to go from XE16.2 to XE17 after more than five tries, so I’m wondering if due to the recent issues with updates bricking Glass units that Google is now doing staged rollouts like they do for their Android apps in the Play Store?