I’ve just restored factory settings on my Mac Pro and when I now turn it back on a get a file symbol with a question mark an

[simmstx]

any advice on what to do next?

 

[BadAsAl]

Can you get your hands on a bootable Mac Os or Mac OSX disk (DVD or USB) and boot from that to install?
What happens if you hold Command R after the chime, do you go into a recovery environment?

 

[daffputrw]

i have that issue too about month ago. The problem is the filevault system on your mac. Your disk is encrypted by the filevault. Try to reinstall the os. and if u using the high sierra/sierra open the system preferences, then go to the security & privacy, after that look up to the filevault and turn off that. Or u can open terminal and paste this "sudo fdesetup disable" without ("). After that type your password and you're done.

 

[punnajiuk]

Apple Cleaned my Mac Pro and brought it to Factory settings. My Iomega was working before I went for work on Laptop. Now when I attach the HDD OS X Base System comes up.