Testing an NT display with the module, I found that the feedback for power status wasn't what the display actually send. I modified the module with the actual observed feedback. Here's what I used:
Power ON:? \x7F\x09\x99\xA2\xB3\xC4\x02\xFF\x01\x37\x01\xCF
Power OFF: \x7F\x09\x99\xA2\xB3\xC4\x02\xFF\x01\x37\x00\xCF