I can help you guys out. Some days ago I bought my moto 360 and had some trouble updating it to 6.0 (Marshmallow). I’ve searched for a long time on the internet an found after hours a solution.
First off, do yourself a favor and delete the lastest version of Android Wear on your phone. While you’re at it, be sure to get rid of Moto Connect & Body as well if you have installed it. The Problem is that the android version on your watch MUST fit with the version on your phone so let’s go on.
Step two, disconnect your Moto 360 from your phone in the Android wear menu on your phone. Factory reset your Moto 360.
Step three, on your watch: go to settings and then versions (the location of this menu point can vary). If you have Android 4.4 installed, you need Android wear 1.0.5. You can download it here to your phone and save it somewhere you can find it. If you have Android 5.1.1 installed on your smartwatch, you need Android wear 1.3.0. You can download it here to your phone and save it somewhere you can find it.
Step four, install this APK. Reboot your phone for good measure, and connect your Moto to your phone using the version of Android wear on your phone. MAKE SURE TO NOT ALLOW ANDROID WEAR ON YOUR PHONE TO UPDATE IN THE GOOGLE PLAY STORE.
Step Five, once everything is connected, on YOUR WATCH, go to settings –> about –> software updates. This step takes a LONG TIME, around 10-20 minutes, and your watch must be over 80% to complete this. When it finishes (the green circle wraps all the way around the X) it will ask if you want to upgrade. Tell it yes. When the watch finishes and reboot, FACTORY RESET IT AGAIN.
Step Six, With the watch reset, remove android wear from your phone, and do a fresh install on the play store. Now connect your phone to your watch. You should no longer have any issues. Go ahead, install Motorola connect and any other apps you want to have, and most importantly, ENJOY YOUR NEW WATCH!
extract from http://forum.xda-developers.com/moto-360/help/moto-360-wont-update-4-4w-2-t3205417
HUGE THANKS TO wydra91