Have you activated the new DHCP scope? Sorry, have to ask. Might also be worth manually releasing the old IP address from the IP Phone.
Press the settings button on the IP Phone, go to option 2 (Network Configuration). Scroll down to DHCP Address Released and type in **# on the phone. This should then give you the option to release the ip address. Reboot the phone, change this option back again and hopefully it'll pick up a new IP Address from your server.
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...