Just got a 95 mustang, trying to get it started. Inertia switch is reset properly, but I'm not getting power to the fuse box under the hood. The horn works, and the car turns over and even runs if you spray starter fluid in the intake, but it won't start on its own. Any ideas on what I should check?

Also, possibly related is a relay clicking on and off repeatedly in the rear next to the inertia switch when I open the driver side door. Not sure what that could be.