1993 w124 300D electrical
Guys, I need some help. Hopefully someone has either ran into a similar situation or can diagnose what had happened. A couple of days ago my daughter tried to jump a dead truck battery with my 300D. The diesel car was running when the battery cables were attached. The cables on the car were correct, however she got the clamps on the truck crossed. Big, big spark. She switched the clamps on the truck battery and the truck started as expected. Once she shut off the 300D, it won’t restart. In fact, there appears to be no electrical power at all. When the key is at start position, there are a couple dash lights that will lumenate, the windshield wiper slowly actuates and the car seems to go thru it’s door unlock sequence...
What I’ve checked.
1. Checked battery voltage. 12.5v
2. System voltage, checked at cigarette lighter is 5.7v
3. Replaced OVP. Top fuse was blown.
4. Checked all fuses.
5. Checked ground at bell housing.
Is there possibly a relay that fried?
Any help would be appreciated, I’m not sure what device I should check next; ignition switch, starter, alternator?