Had a booting issue with my first QC after a month or so. It just wouldn’t go past the blinking lights no matter what I did. Thankfully Sweetwater overnighted a replacement unit. When I tried searching online for the boot issue I found a decent amount of people experiencing the same thing.
Recently did a tour and the opening band had a QC. Theirs also wasn’t booting up one of the nights when they went to start their set.
With the reply’s I received from @ndsp_staff im in friggn limbo as I gig weekly with the QC… 
I tried to post about this on the Neural user Facebook page and as it’s run by neural they wouldn’t publish my post… it BS Neural…
Another 2 weeks go by @ndsp_staff … every time I turn on my QC it fails to boot up… I then need to turn the power off, then on again to get it to boot up. still no fix… awesome development update we’ll be able to use plugins on our QC… if it boots up…
Just received this from NDSP:
Hi Justin, This black screen on boot issue is addressed in the next CorOS update, which has already been released to beta testers. We hope to release it early next week if no other major issues are found.
Thanks for your patience
Best regards,
Neural DSP Support Team
Let see……
thanks for sharing that. Fingers crossed…!
I am now getting this problem too. I just started a few days ago, and nothing has changed. It may be heat related as if I leave QC in the blank screen state for a while and then cycle power, it boots up fine and stays operational.
I’ll keep monitoring to see if this gets worse.
My cortex also does jot start. I am really confused and disappointed…i never had a problem before with any equipment…
My cortex will not start. And i have to play…how do other people this? 2 decibes. Never had this before and probably end of cortex story for me. Not reliable
what power supply are you using?
Same problem here. In my case, it started after using Cortex Control on my Mac for the first time. After creating some presets and returning to the Quad Cortex, I noticed they disappeared. My old presets vanished as well, although their names were still present. Following this, my Quad Cortex began blinking blue lights in a loop. Somehow, I managed to make it boot and performed a factory reset. After that, while using it, an OS error appeared, indicating that some capture was removed due to an error. Then the Quad Cortex started blinking blue lights in a loop again.
Hey Ricardo! Did you have any luck on this? I’m facing the same problem.
Yes, I replaced the internal SD card and that fixed the issue.
While not recommended, this solution worked for me.
Before the swap, I created a clone of the original SD card using imageUSB by PassMark Software.
This process can be time-consuming.
SD card details: 32GB SanDisk C10 A1
Thanks for all the details, man. Probably will do it if support is not provided. I was reading about that and I’m tempted to try it since all of the problems I’m having, is a strong signal (Factory presets appear with nothing inside and when selected the name disappears, and QC turns off while writing data) that the SD card is corrupted or something. It would be extremely helpful if NDSP made the firmware available to download.
NDSP does not make the SD Card OS available for download.
What version is your QC, 2.xx or 3.xx?
Yeah, which is a bummer. 
I’m using 3.0.1, tried to update but it keeps turning off when downloading or installing.
I have an online QC_IMG.iso backup of the system but it is version 2.XX.
The procedure that has worked for some people is to carefully remove the SD Card and clean and replace it.
I will keep in touch with C. Borges and NDSP Support to see what happens. If I do not receive support, this option will be my last resort. Thank you for sharing all that information!