Sadly most update instructions don't mention things like overclocks etc. It is also never wise to use the windows flash option, the instant flash option from within the BIOS is by far the safest and most reliable. 

Swapping out the BIOS chip is pretty straight forward, I usually use a small screwdriver to gently pry out the old chip then making sure the new one is oriented the right way (the small semi circular cutout on the socket should align with the small semi circular divot on the top of the chip on one side), gently push it into the socket being careful the pins do not bend.  

I prefer getting my BIOS chips from the source (ASRock in this case) but if the Ebay chip seller has a good rep and feedback you should be OK with it. It isn't a huge sum of money to worry about anyway. 

First up I would like to clarify what bricked actually means:

Bricked (in regards to motherboards) : The board will no longer post, typically caused by a bad BIOS flash. The term is used because in this state the board may as well be a brick for all it's practical use in a PC. 

Your issue is not a bricked board it is a glitch caused by the flash. I don't mean to be critical here, just informative. We have responses we give in the case of a bricked board (easily correctable in most cases) but these do not apply here.

Could you provide your full system specs for us please.

The watchdog timer error is usually to do with a timing issue, either the CPU is being misread or the RTC (real time clock) is out of whack. You can try performing a full CMOS clear as described here, this should reset the RTC and rule it out as the culprit. 

[edit] Or did I misunderstand your post? Did the windows flash utility cause a BSOD during the flash process and subsequently the board no longer posts?