Most likely a bad ground under the paint...
EZ to troubleshoot...
Make a long wire lead of 14 guage or higher...
1. Ground 1 end to the chassis or battery -
2. Turn the headlites ON
3. Ground the wire lead to the headlite housing

What happens?
A. If the headlites turn ON, then you have a bad ground
B. If the headlites don't turn ON, then you have no 12V+ going to the headlites, need to recheck wiring harness, bulkhead connectors, headlite switch and lo/hi beam switch

Just my $0.05...