Flasher Units...

Doc.... You didn't mention that you had the grill off.

When I replaced my left front fender I disconnected the front turn signal light. I discovered that unless the ground was connected ( or the connector for the turn signal and the ground, I'm old and forgetfull)

The turn signals would just light but not flash.

Could that have been part of your issue?

Coincidentally a bad flasher and a disconnected ground?