The chance for BIOS corruption is a readily understood risk. An improperly coded BIOS file, a bad flash routine, a power failure, and a variety of other problems can occur during the update.
Even after a failed flash, a potentially dead motherboard can possibly still be recovered. Most BIOS manufacturers (Award, Phoenix, AMI and Insyde) now include an option known as Boot Block protection. The Boot Block sector is write protected, thus it can only be damaged if the flash utility is explicitly directed by a command line switch to overwrite this EEPROM memory range. The Boot Block can load the most basic BIOS functions for the simple I/O operation of ISA video, floppy drive transfers, and keyboard input. Luckily these features are all that is generally required to rebuild the entire working BIOS.