NOTE: The BIOS installation procedure used in this case is only really necessary when a Windows OS is not available which HP update packages are targeting.
The HP Mini 210 can certainly boot from USB. This can be enabled by going into the existing BIOS. Hit the Esc key when powering the netbook on. Right arrow key navigate tabs over to "System Configuration". Down arrow key to "Boot Options" and hit enter. Down arrow to "Boot Order" and hit enter. Down arrow to highlight/select "USB Diskette on Key/USB Hard Disk" and press the F6 key repeatedly until that row rises to the top of the list. Hit F10 key to exit and save.
Now that the HP Mini is enabled to boot from USB make a bootable USB using Gandalf's Win7PE, 2GB+ download so be ready for that, from which you may install the bios update. Use rufus to push that the downloaded Gandalf's Win7PE ISO file to a USB drive. Make a copy of your HP bios update package to the USB drive somewhere in a folder you can navigate to easily like "Other". Take the newly created bootable USB drive over to your HP Mini 210 and boot from USB. Once WinPE is launched you may navigate to your bios update package, assuming sp55494.exe, and run it.
The update form should look like this:
![InsydeFlash Bios update form.](https://cdn.statically.io/img/i.sstatic.net/iz8Wh.jpg)
Sadly, HP advertises most of their laptops can use this procedure to update the BIOS; See section labeled Recovering the notebook BIOS using an external storage device. However, with the HP Mini 210 I didn't find it functional. The EXE also was not able to run in DOS mode which hasn't been the case in other computer experiences had.
An alternative to this approach would be to install Windows OS first then proceed with installing the HP BIOS update from within the Windows OS.
As for installing a Windows OS to devices lacking a CD/DVD media drive I also recommend rufus. Use this procedure to install from USB without a CD/DVD media drive.