In the `main` module, you declared the `led` output signal, but you did not drive the signal.  In other words, `led` is not connected to a driver.

I think you simply need to connect it to the `LedScan` instance:

    LedScan scan (
		.clk(clk), 
		.leds0(flash_data_out),		
		.leds1(row_1),
		.leds2(row_2),
		.leds3(row_3),
		.leds(led), 
		.lcol(col_wire)
	);

When I make the connection to the `leds` port, the `led` signal becomes known (the x's are gone).  Also, I don't think you need the `led_wire` wire.

I think the same is true for `col` and `col_wire`.