- Download the BIOS installer from the dell website. For example, http://downloads.dell.com/FOLDER01530518M/1/E6500A29.exe
- Drag and drop the file to a CMD window, hit space once, then type /writeromfile
- Drag and drop the file to a CMD window again, hit space once, then type /writehdrfile
- Rename the .hdr file to include just the machine name, in this case E5600.hdr
- Put on a FAT32 formatted USB drive
- Remove the battery
- Plug in usb to the left side slot (try each other slot if that doesn't work)
- Hold end key and power button, then plug in power cord.
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.(https://www.bios-mods.com/bios-recovery/)
Another post for a Vostro laptop contains very similar instructions: http://en.community.dell.com/support-forums/laptop/f/3518/p/19593398/20675627#20675627.