You should be able to force flash bios, but it could brick your board. But if you still are determined to flash it, here is how it should work. Go into bios and in easy flash select what file you want to flash, you should get error message so once it pops up, write on keyboard word risky. This most of time works on asus boards to skip bios checks. But do it only if you are prepared to maybe get bricked board with nearly zero chance to get it working back.