Flashing H200i to IT mode to use in R510 12 bay

[Sir_Zeke]

Hi, I have been at it for far to long without any progress. I looking to move from my Synology DS918+ to my new/old Dell R510 12 bay with truenas. I done all the checks on server and only thing that is left is to flash H200i to IT mode and do something to run in in storage slot with 2 SSD in internal caddy, one for boot and second for plex. I have old pc that I used to flash H200 successfully??? don't really know as I can install truenas on one of the SSD but after restarting server I cant boot from SSD. Please help me figure out if I did something wrong when flashing H200i? Or do I need to change something on R510? I have a old PC that I used for flashing and it's UEFI (not really sure what that means but the DOS part of tutorial I was fallowing didn't work and only way to progress was to use UEFI version). Please help me out with some guide of how to do it for 5 year old brain as I'm at a lost so far.