If you are seeing the registration rejected message on the phone, it could be that you have either not added the device to Clall Manager or you have not enble auto registration on the Call Manager cluster.
I would also have a look at this document to check the auto registraion:
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...