Samsung DLP HL-P5663W 56" TV "comcast volume working adjust" Questions

Comcast HDTV box with the tv. My new Samsung DLP 61 inch tv has a similar problem. The remote works, and then after it warms up for a while the tv won't respond to the remote. Evidently 2 good remotes

...volume, or Mute, to clear the displays. Does the clock have a replaceable battery? Accessible? (TV works fine otherwise, in my mid-80s not likely to replace it!) Thanks jvmx@comcast.net do you mean ...

...comcast remote, Push and hold the setup button. The TV button will flash once, and then twice more. After the flashes, you will input a 5 digit code, if it is high definition, the codes are 11454, ...