Is your computer plugged into a USB flash drive or a removable hard disk? Or, does the computer have a card reader with an SD card?
If yes, please unplug them all and restart them.
If the USB flash drive is not inserted, restart the computer, press F2 to enter the BIOS, do nothing after entering, and exit directly, and the computer basically returns to normal.
The global BIOS manufacturers are mainly Award, Ami and Phoenix. The red triangle you mentioned is the Logo of AMI company, and the so-called ASUS BIOS is actually the BIOS above and the coat of ASUS, which fundamentally determines the instability of ASUS motherboard.
All ASUS motherboards and computers will often show you the Logo, so that you can't enter the system. As long as you enter the BIOS and then exit, you will generally be fine.
If not, check your hard drive to see if it is broken or something.