Ah yes. Thank you. One time boot menu. Now I see where you were going.
The Z68 was one of the best boards I ever owned. Mine was an Asus Pro version that had a legacy BIOS. It was stable and reliable, that is until I needed to flash it in order to support a IvyBridge chip. This wasn't a let's flash to have the latest BIOS move on my part.
SandyBridge only supported PCIe 2.0. I needed Ivy for PCIe 3.0 which was supported on the Z68 and my video card. I played a lot of Command and Conquer, Warcraft and Diablo back then. Like you, I went through a manual flash, with the system connected to a UPS, and made a backup of the existing BIOS.
I performed the flash which said it was successful, but ended up with a brick (like you). Black screen, flashing cursor and a dead unresponsive board. Asus boards had something called CrashFreeBIOS which was promised to allow the system to be booted from the MB CD and re-flashed/recovered. That was a bunch of marketing BS. It didn't work. In fact nothing worked. I spent a week searching for a solution. So I contacted Asus and got the run around. In the end, I purchased another chip (from Asus) with the BIOS rev needed for Ivy. However, the experience left a bad taste in my mouth. One that ultimately cost Asus my business (13 yrs) worth. This was primarily due to their handling of the case and supreme lack of customer service. So 6 yrs ago I walked away. These types of issues happen, but how a manufacturer handles a claim while a product is under warranty matters.
So what's next? Z390, 490?