the bios should work. unless your card is a different revision - Ive had that happen before... IDENTICAL 5850's from sapphire, but one was a different revision and i pretty much bricked it when i tried to flash it with a custom bios from my other card....thats when i found out the bios versions were incompatible and it was a different revision (always make sure you check if you ever go crossfire)
as for the whole RMA thing, sure it sucks, but IMO they should still cover it whether the card is secondhand or not so long as its under warranty.
They would never send you a new bios anyway. even sapphire wouldnt send one to me when i made that mistake flashing the wrong bios onto a 5850 that looked exactly the same as my other one, despite me telling them i knew where i went wrong and i could fix it in less then 30seconds if they would supply me the correct bios.
and the shocking thing was i was upfront and honest about what I had done with it instead of just telling them it was DoA like most people do if they mess up something theyve owned for less then 1hr.
Luckily the shop I ordered from still had stock and a replacement was sent out and arrived within the week.
Company Procedure just means their hands are tied. Fortunately some forums have reps from hardware manufacturer's (who are also enthusiasts like most of us here) and they try to help out where they can.
In our case ThermalTake, BeQuiet & NXZT havent started making pc components yet apart from powersupplies, cases, fans, fan controllers and peripherals etc etc. so so they dont really need to deal with the same hardships as GPU partners do.
“I used to be a serial upgrader like you, then i took a downgrade to the knee” -FreedomEclipse