I feel your pain.
I did the same thing last winter (embarassed to admit, but it was dark, and raining, and doh!!).
In my case this fried the Alternator itself, melted the Alternator harness(at and near the Alternator connector), and killed the Stereo.
Also blew the OVP fuse.
Luckily (thanks OVP!), that was the extent of the damage.
1) Check the output of your Alternator to verify it is still charging.
2) Check the condition of the Alternator harness to make sure it did not melt to the point where it could short out.
Sorry, and best of luck...
1986 300E 5-Speed 240k mi.