I had the same dead battery issue. Once I replaced it everything went back to normal and was communicating with Line 6 Edit. Also, I have the V2.50 software uploaded as a .SYX file so you can no longer worry about using Monkey to get the software into your amp.
This is the firmware for V2.50 in .SYX format for the VETTA 2 amp head.
https://www.facebook.com/groups/647483512018911/