A CEM+ doesn't seem to generate defaults or accept a config by any means. The key symptom that often gets missed here is that the screen says "Rack X/0" where X is greater than 1.
Description/Explanation of Issue
If the CEM+ generate defaults/no config screen says "Rack 2<or more>/0" this creates a glitch wherein it will not take a config.
Simply reboot the CEM+ while holding down the double back arrow button until it says "abort boot" whereupon it will deep clear any and all configs and make it ready to accept a new one.