All servers/PCs either have trust domain issues or cannot contact a DC

I was helping a friend who has a small business. The guys that upgraded her server really did a bad job. The new DC that was supposed to be the primary and only DC had a lot of errors. I fixed a lot of them, but then I was stuck trying to get the File Replication Service to start. All the FSMO roles are on the old 2008 DC. I was being careful, but somewhere I screwed things up bad. The thing was already falling apart, but I pulled the final thread.  

Anyway now all servers and PCs either have a trust relationship issue, or a cannot find logon server(or something similar I'm home now) issue. Including the mail server which is not working now.

The DC with the FSMO roles is Windows 2008 R2 standard.
The other DC is Windows 2012 R2 Standared(the one with the original issues. 
There are also two other DCs in remote locations that are read only. 

I tried to change the name of the PC in the domain. That didn't work.. I didn't unjoin and rejoin. But that isn't going to help me with my Exchange server. 
I have rebooted of course. I also tried to power down the 2012 DC to see if it was causing the issue.

Any ideas? I am seriously thinking of demoting the 2012 server. Powering down the old 2008 DC. Creating a new domian and rejoining all PCs and recreating the profiles. THat part would be simple enough, but I don't know how well the Exchange server would play.