You would need the recovery CD ISO for that.
You would have to have a local copy of that from when the server was setup, or when server was still a supported product and recovery CD was still downloadable.
Those are long past support, and haven't been posted on the Cisco site for years.
You may be able to try mounting some sort of centos live CD ISO, and see if you can run a fsck type process to clear up the file system issues that got triggered by the power outage.
I would make sure your management understands they are running on End of life, End of support, hardware and software, that has Zer0 support options, and need to budget for a replacement system which would be something like BE7000 model appliances at https://www.cisco.com/c/en/us/products/collateral/unified-communications/business-edition-7000/data-sheet-c78-730649.html?cachemode=refresh#PlatformModelOptions
BE7M-M5-K9
Kirk...
