Things I can think to check:

- obviously check power to each chip, btut it hash multiple connections for power so make sure it's getting to all of them. It's pretty hard to fully test that since the pads are underneath. So you have to kind of go by inspection and whether it looks like it's "dry".

- check the reset pin, it needs to be high. Don't measure at the resistor but try to get right to the pin. If it's still low then it's being held in reset.

- check the clock is getting to those chips.

- If the chips are both sequential in the chain, then the first will block the second, so focus first on the one lower in the chain. I don't have a good diagram yet - todo. The chain order is

Bank 0: U6, U8, U5, U7, U2, U4, U1, U3
Bank 1: U9, U11, U10, U12, U13, U15, U14, U16

The weird order is because I laid out the chips before we had the docs, so took a guess as to which way the pins oriented for chaining.

- what method did you use for soldering ASICs? oven or reflow air gun? I had one that shorted power and I couldn't see it. I was lucky that reheating with the air gun and giving it a small bump with tweezers got the bridge under to clear. I've found that less paste is better than more.

- if you have a scope then view the data inputs, and chain outputs.

- you can alter the code that sets up the NonceRange values to push zeros for other chips and a start value for that chip close to the expected nonce. That will have that chip find it first before others, so if triggering then you should see what it outputs. But you cannot know if it actually came from that chip except by timing - quickly, or later in the the cycle. Init to just before the nonce on that chip and just after for others gives max difference between them.

- note the chip order above. If any chip is not working then ones after it could be but may not get data from up the chain.

That's all that pops into my head atm.