your generic RAM is quite hit or miss (there is another thread regarding your generic memory). try the following RAM model if you have any of them.I've done exactly that, I first tried both dimms at the same time, then tried each dimm individually on each of the 2 dimm slots.
Memory type - 4X70G88319 - 1x 16GB DDR4-2400 RDIMM PC4-19200T-R Dual Rank x4 Replacement
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There is a .flash file if I remember right that can be flashed directly thru iLO. I can get you the path once I am at my PC.I would certainly try to update the BIOS via the iLO if its possible. I managed to get the ISO that was so kindly shared however I am unable to find the actual bin that would work while updating from iLO. My understanding with the iso - is that it should be booted from where as I can't even get THAT far. Does anyone the BIOS update as separate installer?
As for memory - I can certainly try I don't believe I have that exact Hynix but it is a similar DDR4-2133 2Rx4.