"What you ask them to do is totally unreasonable. You want them to build boards using your gerbers, then if the result doesn't match the test board (which they have no control over) you want them to throw their work away and return you the money. They probably didn't understand what you're asking, because nobody in the right mind would ever agree to such conditions."
Whole load of totally wrong assumptions there, but hey this is social media
I paid for the "tooling" plus the cost of making the one board. I merely asked them, when they BBT the panel they made, to
also BBT the panel I sent them. Extra labour = seconds. If the two don't match, then there is a problem, I lose the NRE charges plus the panel cost, but detecting that is better than getting a few k boards back, populating them, and finding they don't work.
Many years ago I got a few k boards back from a UK company. BBT passed of course. Populated them all. First one tested blew up the PSU. Turned out that all the vias were plated to all the inner layers
Yes this is rare nowadays, but the risk is very high. Especially when one has struggled buying the various chips at extortionate prices of today, and even then managed to get only just enough.
I have used this process for 100% board validation before, and never had a problem.
The reason I posted this was not to get sympathy
it was to find out whether there is some issue with BBT which prevents two panels being tested from the same data. Of course I can't see how that could be possible. I am 99% sure these people just struggle to google translate between Chinese and English.