I am a Quad Cortex user.
I bought that 3month ago.
My machine did not work last week, so I replaced that machine.
Now, I have a brand new Quad Cortex.
My point is that I need to check the machine has problem or not.
What should I check to know it has problem or not?
Tone would be suggestive, otherwise maybe start with what issue(s) you had prior and ensure your issue has been resolved.