Urgent Ubuntu RAID Boot Fix

My Ubuntu 22.04 server with 16 GB of RAM refuses to go past the GRUB / boot splash after a simple power-cycle earlier today. Nothing else was changed—I literally shut it down, powered it back on, and it stalled. The machine has what I believe is a RAID 1 setup, yet there are three SSDs in the array, so I’m not completely sure how it was configured. Unfortunately none of the data is backed up, so recovering the system intact is critical.

The box is sitting beside me right now and I can provide live console access (iKVM, IPMI, or a video call while I hook up a keyboard and monitor). I need to be operational again by tomorrow morning, so I’m looking for someone who can jump in immediately, diagnose the boot failure, repair any GRUB or mdadm issues, and verify the integrity of the RAID set without risking data loss. If additional steps such as fsck, reinstalling the bootloader, or re-assembling the array are needed, please guide me through them or perform them over SSH once the system is up.

Deliverables (acceptance criteria)
• Server boots cleanly into Ubuntu with all services reachable.
• RAID array is assembled and synced, with a clear explanation of the three-disk layout.
• Memory check results confirming the 16 GB are recognised.
• Short post-mortem so I know what went wrong and how to avoid it next time.

Tools you’ll probably lean on: GRUB-rescue, mdadm, smartctl, fsck, and any live-USB recovery environment you prefer. I can burn an ISO or plug in a prepared flash drive if required.

If you’re available to start right away and confident in deep Linux/RAID troubleshooting, please let me know your plan of attack and an estimated timeframe.