As already stated BAT does not have an option to update the DN, so the only way will be the following:
Make an Export all Details of the phones, then open the file and change the DN, then delete the phones and make an import all details of the file that you just modified.
Keep a copy of the file that you exported just in case.
I recommend you to try it with only a couple of phones until you feel comfortable with the process. I understand that is not what you want to do but there is no other way, except to do it manually through the CCMAdmin webpage one by one, which is actually the safest way.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...