My guess is that the model of mcs-7835 server you are trying to load the Telephony OS on doesnt support 2000.2.3. The newer mcs-7835 servers require Telephony Operating System 2000.2.7 and 2000.2.7a or later. Hope that helps.
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...