The CEM also doesn't seem to work either. Codes can't be read by a scanner. And the windows, lights, power mirrors, and heater/A.C. all don't work

 

Start by looking at the under-hood fusebox(es?). Don't know what kind of vehicle you have. But with that many unrelated systems off-line, my bet is that there's a problem with power distribution to the fusebox. Just check across the leads that SHOULD be carrying battery voltage to various places - I'll bet you find one that isn't.