Have theory that A3 was build on D3 and this is the reason some A3 (including mine) have problems with hash boards - appears/disappears, hashing/no hashing, all asics few only and then turning 0000 into xxxx...
Nothing is helping to solve: rebooting, restarting, resetting, plugging / unplugging, each by one, separately, adding two AWP++ , changing controller cables 1/4, 2/4, 3/4, 4/4 Even flashing ( thank you blissz) - NOTHING
But funny my D3 with A3 firmware turns into A3 miner, even connects to the SIA pool, but not hashing and after moment all asics turns xxxx
This suggest than sia network or "brick attack" on 24th is not the real problem. The real is that bitmain cleaned D3 stock transforming them into A3 thought
____ NOW the funny moment. If/when somebody finds out hot to avoid that wall to make D3 (with A3 firmware) hashing on SIA network....

....... ALL D3 would finally be able to deliver ROI
Actually been working this angle, have a pretty good idea of what makes a miner a D3 or and A3, but i need a D3 to test or someone with a D3 to send me some data to try to turn my A3 into a D3.
There's pretty good reasons for bitmain to do something like this if they could. It would massively increase profits for them to have a ASIC chip that could be re-seeded to different algos.
Also if you want to dump firmware the bitmain way...
nanddump -f /initramfs.bin.SD /dev/mtd8
nanddump -f /am335x-boneblack-bitmainer.dtb /dev/mtd6
nanddump -f /uImage.bin /dev/mtd7
nanddump -f /u-boot.img /dev/mtd4
You'll have to hex edit those files afterwards and remove the trailing FF's to make them exactly like bitmain sends them out.