Pffff that is not ok
If you can't boot your computer when you insert your card, that is a big problem.
I have more than 60 cards, from which 48 are Polaris.
I played with BIOS-es a lot and i flashed them many times
So, if i bricked one card i just started my computer with onboard card as default.
But never happened to freeze the comp because of the card.
I suspect that it could be a hardware fault.
Anyway, if you can't boot computer you can't flash the card from computer.
You must use the external BIOS programmer for this case.