If it works yes, at least it's much newer, and cache devices should be automatically assigned, download the 6.9.2 zip and extract only the bz* files overwriting existing ones.
No, the solution is this, though sorry I linked another post that linked to this one:
https://forums.unraid.net/topic/119502-bzimage-checksum-error/?do=findComment&comment=1120488
You could revert by just overwriting the bz* files, if you overwrote everything most settings will be gone, do you have a backup of the flash drive? If not see here:
https://wiki.unraid.net/Manual/Changing_The_Flash_Device#What_to_do_if_you_have_no_backup_and_do_not_know_your_disk_assignments
Shfs is crashing when the mover runs:
May 18 03:40:05 Apollo kernel: shfs[8826]: segfault at 0 ip 000000000040277f sp 000014f2d44518f0 error 4 in shfs[402000+b000]
Unfortunately can't tell why it's crashing, make sure the files being moved and not being manipulated by other apps/dockers, that is known to sometimes cause issues
So it's working now? Only thing I find about the NICs in the log is this:
May 19 02:57:49 Tower kernel: pci 0000:05:00.0: invalid VPD tag 0xff (size 0) at offset 0; assume missing optional EEPROM
May 19 02:57:49 Tower kernel: pci 0000:08:00.0: invalid VPD tag 0x00 (size 0) at offset 0; assume missing optional EEPROM
Unlikely that the update is related, and basically same issue persisting after downgrading confirms that, check/replace/swap cables on disk1, you can also look at the LSI BIOS, if it's not detected there it also won't be in Unraid.
If you never set a password it should be asking to set one up:
If you don't see this do the recovery password procedure and you should see that at next boot.
You are having some strange issues, first try booting in safe mode, if that doesn't help I would consider re-creating the flash drive and start with minimal config or re-configure the server.
Try re-creating the flash drive, backup current one, download v6.10.0 and unzip the files after formatting or use the USB tool, then restore the config folder from the backup.