Yesterday, I upgraded the firmware on our Bolt EV - it only takes about 15 minutes. Here's the link to the download from the MyChevyBolt.com forum:
https://mega.nz/#!mgZyVZLY!tGpiKZFNU...q873JnRd0YpxWg
Here were the instructions:
"Unzip file to root of 16Gb USB flash drive Unplug anything from Bolt USB ports
Power up Bolt Insert flash drive with update on it Agree at "do you want to update" prompt on center display
Wait 12min- watch progress bar on center display "Done" will appear on display, display will shut off in 2-3min
Remove USB flash drive, turn Bolt off, wait 30sec or so, turn Bolt back on... display takes a bit longer to boot first time after update
Confirm you're on 14.4.2