Copied from reddit...

S21 from vnish to stock FW, shoot me...

I'm sure it's something simple that I'm missing, but I've already got the S19 firmware reverted back on the S21 from vnish.

But how the hell do I use the damn S21 .bmu file for putting the S21 firmware back on the S21 so I can send it in for warrantable repair ?!?

OK, off to bed, ty... but tickets made. I just gotta box the fucker, more or less.