Information is not gone until you say it is gone.
All the info on those hard dives may still be there, but that particular computer may have blown some memory so it does not boot up properly. Power sources fry so the towers wont boot up or turn on.
Have had the boot sectors on the hard drives go bad so it won't boot up.
Clone copy the drive and and write it to a brand new hard drive, in the process it will write a new boot sector. I like using Acronis Imaging Software, there are a couple different ways to go about it.
Can also take a hard drive reader set up on another computer and see if it will spin up the hard drive, then go down into the shown folders and see if you can find the information everyone has been working on.
Then copy the info out to an external hard drive for safe keeping, load up another server and copy it back in.
Good to Go . . Have pulled some nasty lost information situations out of the fire, by being careful not to destroy what is left behind. Being patient and taking the time to think about safe ways to retrieve the data.
Being able just to see the data on the hard drive by itself is a big milestone, then you can figure out safe ways to copy it out and put things back into service again.
Having some good luck on your side helps too.
Good Luck with your Data Recovery.