When the computer turns on it copies BIOS into RAM and operates it from there.
You can make changes to the EEPROM that contains the BIOS freely and they will only take effects when you next reboot.
If said changes FAIL to properly write a new bios to the EEPROM you are not supposed to turn off the computer, as doing so will brick your mobo. Instead, keep it on and keep on trying until you manage to get a full SUCCESSFUL bios installation (even if it is not the latest version)
Unfortunately you already restarted the computer so your mobo is now bricked. There is nothing you can do to fix it yourself. If it has a physically removable EEPROM chip for the bios then the manufacturer could send you a replacement chip, but otherwise you would have to send the mobo to them for replacement. (they should have the specialized tools needed to reflash it, and if not, they should still cover it under warranty)
If its not under warranty then you need to buy a new mobo
How to protect your data guide
AA Naming Guide
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