It's been a minute since I last posted here...

Just got this from reddit... So, I switched the S21 from vnish back to the stock firmware, but now I'm stuck... I feel like I'm missing something obvious. I already rolled back the firmware on the S19, but now I can't figure out how to use the S21 .bmu file to reinstall the S21 firmware. I need it back to send it for warranty repair! Alright, time to hit the sack, thanks... but I've already opened a ticket. Just gotta pack the damn thing up.

On an unrelated side note being that I've suffered one hack in the past here, I love seeing OTP now and that's enabled !!!

Okay so upon a more recent video I found, it  Seems I need a download for a tfcard service pack where there is only currently firmware which are the .bmu files for the S21. So am I stuck with sending this thing in with stock FW, even though it's S19 on an S21 lol I mean I don't care about the money for saving warranty. They just want stock FW, but they may not even look at board 2 w S19 on an S21... IDK.

you can find it on Zeusbtc or request it from Bitmain support. https://www.zeusbtc.com/firmware-download/details/4957-antminer-21-series-firmware-download Also, what error do you get when you use vanish webpage to upgrade the firmware using the .bmu file?

Long time since I heard from you. https://altairtech.io/product/antminer-amlogic/ Ask them they are usa based They may help

You can't use .bmu file for SD card flashing. All SD/TF card  image for newer units was removed from bitmain it's no longer available use the link provided by mikeywith above make sure it is .zip or .rar file. You will need an SD card to flash the unit; make sure it is formatted in FAT32, and then extract all the firmware pack files onto the card. After that, plug the SD card to the unit then run the unit. 2 led lights will blink and it would stop when flashing is done. Make a factory reset by holding IP report/reset button for 5 seconds then release. Then update here and let us know if reverting it to stock firmware is successful.