There is something (or all) wrong that you are doing there.
Have you runned some commands prior to flash ,like checking BIOS version number in the card ,the checksum and idetifying the right card prior to reflash ?As i presume you ve used a second one to see what you are doing.
Have you reinserted the output cable to the card you ve reflashed afterwards or you expected the card to output signal wireless
? This can happen.
Have you changed in mobo BIOS the settings or removed the second card to make the 5770 primary video ?
There is a comprehensive guide about what to do with RBE ,how to modify the BIOS, how to check the file ,how to flash it ,have you read that 100% ?!
Read the flashing guide again ,get the original BIOS of the card from the manufacturer and flash properly , it should work.
In the RBE guide there is also shown that the voltages are linked in some way over there to some power states.If those voltages don t fit the pattern the tweak wont work.The card should have at least 3-4 states if i m not mistaking with different voltages and GPU/RAM frequencyes.I doubt there was only one voltage over there.
If you are not able to make it work again RMA and stop playing with the VGA BIOS.
The guide ,in case you have not read it -> http://www.techpowerup.com/articles/.../vidcard/154/2Edited by Dromihetes - 5/16/11 at 4:33pm