Anyway, regarding testing the chip vs. testing the PCB. Remember, this is what the PCB looks like:

That's with a stand-in FPGA.
There isn't really anything on the board other then the main IC, and 8x power supplies. Each one costs
$25.05547 a piece when you buy a reel of 700, so that is $200.44 for the power supplies. The rest of the components look pretty inexpensive.
As far as the cost in the event of a completely bad chip, you probably wouldn't want to actually
throw it out, but you could easily just set it aside and then go back later and remove the power supplies.
Or as I said, if there's only a problem with one of the 4 completely separate hashing circuits, they could use that miner as one of their own self-mining units.
They made it very clear that they are going to test each unit before sending it to the customer, but only for about 20 seconds each.
There are a ton of "armchair experts" on this board who think they know more then the people actually doing things.
Heh, in formula-1, of course, they throw out the engine after every race

No they don't.
well they rebuild them, from what I understand.