Having read this I am pretty sure there is more to this than you have explained. Suddenly finding the server is crashing? Doesn't make much sense. I suspect you have been economical with the details here.
You have not given any information about your actual server - exactly what model of Proliant, what RAID card does it have etc.
You seem to have managed to install SME with software RAID on to a server with a hardware RAID card. You should probably have used the hardware RAID and installed SME without software RAID. There are usually benefits like caching etc. when you use hardware RAID. I'm also not sure why you'd put 4 disks in RAID 1. Hey ho.
As your server presumably booted OK originally to the first disk, and then software RAID, then something must have changed in your server RAID/BIOS for it to decide to stop booting directly.
Firmware update or similar. You should check the iLO logs etc and use the RAID configuration utility to have a proper look at what is going on. You should be able to boot directly off a disk if a raid array is not detected.
Or check who has been poking about in your BIOS eg:
https://techlibrary.hpe.com/docs/iss/proliant-gen10-uefi/s_Disabling_the_F11_OneTime_Boot_Menu.htmlSome more reading might help you understand your server a little more.
I'd be very careful about messing about with grub unless you absolutely know what you are doing, which by your own admission you do not.
I'd also suggest not trying to install stuff via team viewer, particularly ANYTHING that has to do with networking. Especially if you don't know what you are doing. A recipe for disaster. Get a test VM and trial things with that first.