Looks like the PO installed aftermarket signals? Easy to get polarity wrong since it'd work either way with incandescent bulbs.
If you can, swap the wires where they tie into the wiring harness.
If the led bulb works after that it was polarity.
If it's still not working it's probably the damage to the wires.
If you can, swap the wires where they tie into the wiring harness.
If the led bulb works after that it was polarity.
If it's still not working it's probably the damage to the wires.