I know this is an older thread - but I just had an experience with shop mode after updating my Q950T firmware to 1019.5.
After the firmware updated the soundbar kept switching source, and cutting on and off. I called support. They couldn't even tell me how to factory reset, as it wasn't responding to the +/- buttons and doing an INIT. So they suggested I ship it back to them. I mentioned to support that I see "shop" message. He said that happens after a reset.
I played around more. I discovered that it was in shop mode. And to get it out a google search showed me to press "-" and hold while power is off. Bingo, I was able to turn off shop mode.
And as soon as I did - buttons started working again, and I was able to do a factory reset, and re-pair my speakers. Since then the soundbar has been working great - so far!
Really disappointed that they wasted 6 hours of my day, and in 2 hours on the phone with 3 people couldn't solve this - I solved it myself using the internet! Wow! That's sad.
Anyway, the new firmware works well, and it's good knowing that shop mode is a thing! Hopefully my subwoofer pairs on power up now. That was what started all this - and I was furious when they had me update firmware and caused all kinds of issues, and then wanted me to pay to box it up so they could send me a shipping label! Terrible support Samsung - you can do better.
