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.

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. This is why led is not being set to a known value (it has the unknown value x).

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.