Is it possible to "flash" the firmware on these drives?

It would appear that they have in someway been locked.

I got them from Ebay and they have been taken out of BT Vision boxes apparently.

If it is possible, could someone please give me an "Idiots Guide" to doing it?

Thanks in advance,
Az.

No it's not a cell phone (and even if it was, modern cell phones need specialized tools).
It is not possible neither to give you "idiots guide" neither "smart guide" because either specialized equipment is required AND/OR know how (priceless !!)
MOREOVER : even if you have the specialized equipment above mentioned and know what to do, the drives you would like to use require additional rework otherwise you'll have neverending problems with them during re-use. These are some of the reasons why these drives are on such market.
If you want to outsource, PM .

If the default master password is intact, then it should be possible to recover the drives with a secure erase:

http://cmrr.ucsd.edu/hughes/SecureErase.html (freeware)
http://cmrr.ucsd.edu/people/Hughes/HDDEraseReadMe.txt

_________________
A backup a day keeps DR away.