I had a KP-4000 remote that would show up fine in CCP but would fail when trying to download to it. The factory reset procedure of holding Main + Mute down for 3 seconds and then the Reset button for 6 seconds would not get the remote to factory default and erase the flash memory. I checked to see what Fing (network discovery program for IOS and Android). Fing indicated that it was responding to ping requests and there was one open port 21 (FTP). I used WinScp and connected to a working KP-4000 and copied all of the files to a directory on my PC. There is no password used, just hit enter. Then I went to the non-responding remote and copied the working files to the bad remote. I just over wrote all existing files. The remote rebooted and I was then able to download new code to it.

I am not sure which file or files was necessary to revive it . I just used a brute force copy all. I hope this helps someone else that is having issues. The WinSCP program is available free, just google for it. Fing is also available for free from your phone's app store and really comes in handy for troubleshooting network problems.