I put a new battery in my 2006 Vette and now the clock doesn’t work. Tried what the owners manual said to no avail. 
Any ideas welcomed!

By now I'm sure you've seen that it is an issue with the C6 with a variety of fixes that don't seem to work right.  The dealer that is working on my 2005 convertible says that one of the fixes they tried toasted the entire radio.  Another dealer says that they've tried multiple times and think they might have a solution whenever I'm ready to bring mine in.

Same thing happened to my 2005 C6 Coupe.  There is a great article in the June 2020 Corvette Magazine in the Tech Nerd section.  Read the article.  Download the update from Corvette mechanic Paul Koerner’s website at (https://bit.ly/36S3E5C).  Did this on my Corvette and it works great!  Passed it on to a couple of friends and it worked for them also.  Hope this helps! Thank you to Paul Koerner also.