Just updated all my neural devices to the latest FW (Quad Cortex/Nano Cortex). So far, this seems to have fixed my problem (halleluyah!!!).
Powered the Quad Cortex off and on multiple times in a row - no more noise upon bootup, tuner acting normal.
Now there is a new question:
They seemed to have replaced the Standby with a “be right back” mode wich seems to do the same thing (all audio off, screen goes to sleep) - When I was having the noise problems, at shows after soundcheck, I kept the device in standby always (much like a macbook) and only “woke” it when I was playing to avoid the super annoying noise upon boot….
I guess “be right back” would allow me to do the same? - would anyone disagree here?
I’m not sure that this is a software problem. I experienced this problem maybe 4 times over the years. When it happend it was persistent but I was always able to “fix“ it with a gentle clap to the QC. The last time I opened the QC (I am a Electrical engineer 
) and replugged the ribbon cables. since then it never happend again.
I’ve also noticed in the past that this behavior occurred when using an expression pedal.
I
This sounds interesting.
As my QC has (since its last SW update) not behaved in the described fashion again, I´m quite happy with it at the moment - still out of curiosity, where exactly would you “clap” the device if it was to behave like this asgain in the future?
I grabedv it by the foot switches lifted the front maybe 5cm and then stomped it gently on the floor. ( Case)
When performing this was annoying and the stomping helped without reboot. Therefore I assumed that maybe contacts are the problem.
Br
I also assumed it had something to do with higher air temperature. Also a sign for a bad contact.
So after using the QC in “Standby” mode for nearly 9 months (wich worked fine) I had to reboot it today as I had to switch out some electrical sockets in my house. As expected, when powering on the device the tuner went bananas again and the superbuzz was back.
Whilst usually it took about 1-3 minutes to disappear, now it seems that it is either MUCH longer or constant. I REALLY wish there was a fix - this is driving me insane.
Has anyone experienced similar problems and FIXED them for good?