You could try my remote.conf file a few posts back? It's for a NEXBOX A5
Try it but the same situation. After power off can not wake it up. (power on).
Either with orginal remote.conf copied from oryginal android nor from your keymat - by the way compare it and they are the same.
When try in oryginal firmware - power key is for sleeping (not power of) mabe that is the issue?
In LE when pressing power button device is powering off.