Check your manual. There should be 3 pins on you board named something like J1, J2, J3.
They will have a jumper over 2 of them, like J1 and J2.
This is the normal "on" or "run" position.
Remove the jumper and place it over J2 and J3 for a few seconds, then put it back to original J1 and J2. This will clear all settings in BIOS and reset to everything to default. If you PC boots, you will have to go into your BIOS and reset everything for all your components.
Keep in mind I am just using J1, J2 and J3 as reference, the actual pins will probably be named something different on your board.
This is kind of tough lesson. You should not ever reflash a BIOS unless you are having issues, and the new BIOS you are updating to is written to specifically address the issue you are having. Other than that, updating a BIOS is really pointless, and any slight mess-up during the process leaves you with a dead motherboard.