Of course. Risky is OTT. If you completely mess it up, and do something silly, yes, you can brick a motherboard.
It's actually very straight forward, and takes all of about 10 minutes to do.
Go to your manufacturers website, and download the latest bios. Extract the .CAP file to a USB stick.
It might be worth looking for the instructions for your particular mobo on the website too, and familiarise yourself with them. 10 minutes read time
Once you've done both of those things, reboot your PC, and get into your BIOS. Normally by pressing 'Del' key or F8 or F2 (this will be motherboard/brand specific). Look for the EZflash/Bios update utility within the BIOS menu, and follow the instructions. You will select the newly downloaded .CAP file and follow the instructions to update. It will take a minute or two, and then it will reboot, and you may need to press a button or two to continue with start up, and then you're done.
You could of course, do as TechyInAZ has suggested. That process is time consuming, having to provide proof of purchase, shipping time, and return of the kit.
Given you have the B350, and presumably a Ryzen 1.0 chip in it. Doing the bios update yourself is most certainly the way to go.