Yes, there's some syntax errors there and the code is incomplete. I'm not going to itemize them because I'm going to suggest a slightly different approach that should allow you to help yourself. In general, define the constant
true in wp-config.php. This will cause errors to be listed instead of just getting a blank white screen. The error messages will give you a clue to where and what went wrong. Don't forget to set it back to false when you're done.
I suggest you try to stick to copying and moving code rather than re-writing code as much as possible until you get a better feel for appropriate syntax. Try this for example. Copy the
twentytwelve_entry_meta() function definition to your child theme's functions.php. Do not rename it, and you don't really need the
if(!function_exists(//... part. Be sure the
if() : endif; delimiters are removed together. Copy the function definition once again in the same file, this time renaming it.
While it's important to prevent name conflicts, it's also important for function names to make sense. Try a name like
my_theme_entry_meta(). In your child theme's copy of content.php, insert a call to
my_theme_entry_meta() where you want the content to appear below the title. Leave the call to
twentytwelve_entry_meta() where it is. I realize this all is probably pretty much what you have done already, just making sure we're on the same page.
Now in each version of the entry meta functions, simply comment out or edit out the portions you do not want. Avoid editing in favor of commenting out as much as possible. Editing is where syntax errors happen. As long as you are careful to comment out complete structures, commenting out is a safer technique. You need to be careful with
printf() structures in that the replacement tags ('%1$s' etc.) remain coordinated with the data that follows. Test your code frequently as you make changes, while it can get tedious, you will save time tracking down errors when you know the error can only occur in the one thing you last changed.
With this approach, you should be able to figure out what goes wrong on your own. If you still are stuck on something, I or someone else here should be able to set you straight. Good luck.