No GPS - Software version at 0.00

Also tried to connect to Garmin Express on a Mac with the same results - the computer doesn't see the device either when connected in USB="Garmin" or in USB="Mass Storage" mode

Did you try to clean the contacts of the cable and press them down to unlock them ? When I have USB issues it is the cable pins not connecting properly. It still charges but no usb. Second is to open file explorer on Windows to see if you can see the device. Sometimes Connect only sees it after I opened the device directory. 

I've tried two cables. Neither my Mac nor my Windows device will see/recognize the watch.

I would still clean the contacts in the watch, see if there is nothing accumulated in the side, use scissors to push the pins in the connector , insert again and wiggle it a bit until it finds USB connection (screen turning green) I have had frustrating sessions getting it to connect and it was always the connector, never a software issue for me. 

Thanks. I've cleaned the contacts multiple times. No luck.

Is there anyone from Garmin here?

Not very often, if you want a direct answer contact Garmin Support and use the chat option, usually you get at least some suggestions. 

I don't think a Master Reset works, but you can try the procedure. https://forums.garmin.com/sports-fitness/healthandwellness/f/vivoactive-3-3-music/282613/vibration-doesn-t-work-for-vivoactive-3-notifications-i-ve-tried-factory-resets-and-it-still-doesn-t-work-help-please/1357060#1357060

I have tried to correct a watch for someone where vibration was working in test mode, but failed to work normally and we gave up in the end. So I would still suggest Garmin Support since it seems the device gets into a state where the config settings are messed up and nothing seems to repair them.

Just got off of an extensive support chat with Garmin. We tried several things, including a hard reset. The support tech concluded that the software issue caused by the update was irreparable and that the watch would need to be replaced. Here's the kicker - they wanted $110 for the exchange. A new Vivoactive 3 is currently $189 on Amazon.

Now I know this is an older device. Nevertheless, given that Garmin's own software update is what killed the watch, shouldn't it be their responsibility to replace it? How ethical is it for a device manufacturer to be able to remotely kill a device and not be responsible for replacing it? Seems like a terrific strategy for forcing hardware replacement... 

I asked the support rep if I am assumed to be taking Garmin's software updates at my own risk. The response? "Agent session ended unexpectedly. Carly has exited the session."

BTW, if anyone is interested, the procedure for a hard reset on the Vivoactive 3 is:

1. Press and hold the side button for a full 45 seconds even after the screen goes blank
2. Release the button and leave off for a full minute
3. Press the side button again to power back on

Wow, that was unfriendly. If you have no USB you cannot patch with a beta to retry. You cannot choose to upgrade, Garmin forces that on you when you sync, so if the update is the cause, why treat it differently from a physical design flaw like the watch pin lug issue. They could at least offer a refurbished if they were convinced it was their software update.

Perhaps something failed in the communication (session unexpectedly ended sounds like that), Garmin Support was nice to me for the watch pin lug, although he had to check with his manager to offer refurbished replacement. 

Thanks a lot. Allways good to know.