Calvin7 :
4930K Ivy Bridge-E 6-Core 3.4 GHz LGA 2011 does not fit z370 line.
You can use a Celeron G4900 to flash BIOS to latest version.
https://www.provantage.com/intel-bx80684g4900~7ITEP5YC.htm
Calvin - he mentioned he was buying a i9-9900k cpu
to the OP - one suggestion, use a program like GetRight that controls the download so you know it isn't corrupted
2nd suggestion, is let the bios "age" for awhile before downloading, and then research if folks are having issues with it
i just built a rig with that very CPU and a Z390 motherboard, and when i flashed the "latest & greatest" BIOS for the asrock Taichi mobo, it had only been released 4 days earlier and was either bad or corrupted during download
i should have researched that new of a BIOS release, as after it bricked my mobo (and fried my CPU) i found 2 other posters complaining about that very BIOS giving them issues and at least they were able to reflash to an earlier stable BIOS release
here's the thread if it helps
http://www.tomshardware.com/answers/id-3825393/heads-asrock-z390-taichi-motherboard-owners.html
Asrock is RMAing the mobo, and intel (or the vendor) is replacing the CPU otherwise i'd be in the hole for close to $1000