The ECU is stuck in flash mode. Ask if hypertech can repair ECU's that are stuck in flash mode. If there is no way to recover, you will unfortunately have to simply replace the ECU. We have had similar issues with the older Cobb accessports on the 350z's. Luckily Cobb tuning has been able to recover the ECU's that we have had failures with, but since they never supported the 370z platform they wont be able to help.
Good luck with your issue!
Thanks,
Alex Goodwin
AlexG@motionlabtuning.com