To prevent the failed updates, I have decided to only do updates at my house where I can connect the vehicle to my home wifi before installing. This method has been succesfull so far.My Yukon asked to do the update as I pulled into work yesterday. After work I went out to the vehicle and the battery was stone dead. The update drained the battery and said it was an unsuccessful update. Now the engine light is on and the info system says 'service front collision system".
Trying the update again today except I'll check it in an hour before it drains the battery again.
**UPDATE - it worked this time - no update failure**