Z170-HD3P How to boot in Backup BIOS or both corrupted?

[miracle.flame]

First, let me express how terrible GIGABYTE BIOS flashing utilities and face-wizard are. Such sensitive task as flashing BIOS is a total failure here. Unreliable and faulty.

Background story:
I have flashed my BIOS to the latest rev. F20 and included face-wizard picture of mine which was a 256-color png image with resolution 1024x768. Everything worked out well except the Booting image was quarterly all messed-up in colors. So I repeated the process trying different colors, different resolutions etc. RANDOMLY this process of flashing boot image causes the display driver to fail PC goes into looped bursts of lags and sound disruptions and the flashing process fails. Luckily logging of the Windows session and logging in back returns everything back to normal and you can repeat the process again hoping that this time it succeeds.

I have tried several re-flashings of the boot image but it always came messed-up. Maybe if Gigabyte bothered to explicitly note what are the requirements for the picture loaded or prevented to load one which does not meet requirements this would me much less painful and time consuming.

At one of the failed attempts where display driver failed I had to log off and log in again just to see unexpected prompt from AppCenter if I wish to update firmware. I selected update and during the process again display driver failed for reasons unknown but the flashing continued to the end. then without any prompting it said Rebooting in 5 seconds. And that was my doom.

Current Problem:
Since then I cannot boot up. There are 3 beeps a pause and another 3 beeps. I have searched for methods on how to boot up in Backup BIOS but none of them resulted in anything else than those beeps and bootloops.

Methods tried already:
http://www.overclockers.com/forums/showthread.php/697533-GUIDE-Forcing-backup-BIOS-on-Gigabyte-motherboards
https://www.youtube.com/watch?v=HhI-t5lh_38
http://forum.giga-byte.co.uk/index.php?topic=9462.0

I haven't tried those suggesting to short-circuit pins yet and I want to avoid that. Is it possible that corrupted Backup BIOS was flashed in the process? Are there any other tips how to get to Backup BIOS?

What can I expect to do if I was to claim RMA warranty? I have custom cooler on CPU installed. Is it necessary to replace the cooler when the issue is obviously in BIOS?

[dmdilks]

Recover from GIGABYTE Backup BIOS  (Only for motherboards with Dual BIOS technology)

Method #1:
Shut off the powersupply by pressing the button on the ”PSU” or by removing the power cable.
Press the powerbutton 3-4 times to empty the stored energy in the power supply.
Turn on the powersupply
Press and hold the powerbutton, the system will start the bootup procedure but will shut down after a few second. Release the powerbutton after the system have shut down completely.
Press the powerbutton to start the system.
If this technique was successful the system will boot and you will see the following image.

[miracle.flame]

Thank you dmdilks

I have powered on the case with power supply off. I was surprised how much power there was left before it went off for sure. Then I have powered on the supply and turned on the case while holding the button. System went on and off after a while. I have turned it on again but there were those 3 and 3 beeps and bootloop again.

Doest that mean that both BIOSes are corrupted?

[dmdilks]

Have to tried to pull the battery and clear the cmos? If that doesn't work. The only thing left it to RMA the board.