The problem is a server which due to electricity disruptions is not booting anymore. The OS installed on the server is freeBSD. But the problem is that the disks are not seen at boot.
There would be necessary a few tests: SATA cables change, boot order change in BIOS, EFI knowledge. In short: normal troubleshooting. You should be comfortable with command line and with troubleshooting steps.
The server is located in Barcelona. In the office there is nobody with technical skills. You will need to understand and speak English so we can talk on the phone while you're investigating.
This work requires attention, the server has data on it which cannot be lost