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.