No boot device available

Hello, what server model is this? Any chance this could be second hand?
Is there any changes you made recently? We would like more information on what exactly happened.
Respectfully,

Poweredge T320

no it was installed new i believe around 6-7 years ago.  worked fine till the power outage

Hello, do you see the controller during POST? If not you may need to replace the controller, 
or do you see not see the HDD? Then it may be a disk issue.
Respectfully,

Thank you I was able to install new harddrives and build a Raid 1 now my issue is that once I get to OS Deployment in lifecycle controller and I try to install widows 2012 r2 it gives me an error saying OS Media Validation Media not found. I loaded a usb and a dvd both are showing in F2 boot.  Any suggestions? 

Hello from what I see, what you can do is mount this ISO idrac virtual media.
https://dell.to/3UzlYgm
Respectfully,

@DELL-Young E​ so the issue I have seemed to figure out is the 2012 standard R2 from microsoft is only a evaluation version and it is not accepted as a correct media.  How do I get a real copy to install ISO?  The server did not come with software disks. I have the product key which should be good.  How do I access the correct full version of the software so I can install?

Thanks

If you have a valid product key for Windows Server 2012 R2, you should be able to obtain a legitimate copy of the installation media. Here's what you can do:

1. Download from Microsoft: Visit the Microsoft Volume Licensing Service Center (VLSC) or the Microsoft Developer Network (MSDN) website. Log in with your Microsoft account credentials associated with your product key. From there, you should be able to download the full version of Windows Server 2012 R2 ISO.

2. Contact Microsoft Support: If you're unable to access the VLSC or MSDN, you can contact Microsoft Support for assistance. Provide them with your product key, and they should be able to guide you through the process of obtaining the correct installation media.

3. Purchase a Retail Copy: If your server didn't come with software disks, you might consider purchasing a retail copy of Windows Server 2012 R2. You can find these through various online retailers or local computer stores.

We ran across the very same issue.  We had a PowerEdge T320 sitting on a rack minding its own business for about a decade running 2008R2.  Ran great with updates applied.  After the power surge, the booting screen returned with "No boot device available".  We were almost certain we were running RAID5 but no notes/confirmation could be located.  We had backup, but looking for a simple solution rather than the hassle of restoration.  The boot mode was BIOS and AHCI.  The cmos battery was dead according to the logs after running Dell diagnostics.  The diagnostics tested the drives and they reported no errors.  We set the boot mode to UEFI and booted to a USB and ran a MBR editor to take a peek and the records were null.  In reviewing the paperwork of the T320 is reported shipping with a S110 raid controller.  This is a software-based RAID and stands to reason the MBRs were null.  We felt 99% confident that we can switch the (after replacing the CMOS battery) boot mode to BIOS & RAID.  We ignored the scary warnings about losing data and executed.  It booted up normally and still running.  We feel the dead battery contributed to this problem.