Unfortunately, there's no answer that fits every situation... I burn-in my cables before shipping using an AudioDharma High Power Cable Cooker, but it's the shipping that can undo burn-in, and this can vary from being very minor to having to start all over again like burn-in was never done in the first place. Also, some cables are more sensitive than others, with the silver ribbon cables seeming to be the most sensitive I've experienced so far. On the other end of the scale, the UPOCC copper litz wire seems relatively unaffected by shipping and handling.
I think the reason why is simply due to handling, vibration and temperature changes causing movement of the conductor relative to the insulation. Temperature changes can be responsible as the expansion/contraction of the conductor vs the insulation will be different, then rough handling or vibration on delivery vehicles are more obvious causes. I think the litz wire cables are less effected because the insulation is enamel, so it's basically painted and can't move wrt to the conductor.
I don't think there is a great solution to this, I have not been able to figure it out without going to unrealistic lengths as far as packaging, and even then it may require a special shipping service that doesn't use automated equipment to sort the packages... I've used this to ship expensive components, it's cost is very high and it's hard to say exactly how effective it would be. If you take any cable and bend it around it will sound worse when you put it back in the system and it'll take anywhere from an hour to a couple days to return to normal depending on how much it was handled and what cable it is.
So jtcf, hang in there! I promise it is the exact same cable as the demo, we just got unfortunate with shipping. It may take up to 200 hours to recover, and to be honest there are often more subtle burn-in artifacts stretching all the way to 500 hours.