General tips for my project

So I am working on a school project and my goal is to make a 2x4 ad board with 8x8 WS2812-B LED RGB tiles (here's the exact model). I've got all the things ready and now I need to wire all of it. So I tried one RGB tile and it worked and immediately jumped to wire all of them, I had their V+ and V- wired each parallel to the power supply and they all have voltage (wired them that way cause I thought if I had them all in a series there would be a voltage drop) and wired the data line like Arduino -> Data in 1-> Data out 1 -> Data in 2-> etc. (I used adafruit neomatrix documentation for the info how to wire them). And only the first tile lights up the others do not work (I used neomatrix and adafruit gfx libraries). Any tips and help would be appreciated to get this thing working

Items used:
LED tiles
Power supply 5V 60A, 3x DC outputs, chinese
Arduino mkr1000

My poor paint scheme:
Link

Based on what you have said and your image (please post here, not on another website) you have done everything right. The thing we are missing is your code.

Try controlling 65 LEDs and see if that lights the first LED on the second tile. If it does keep increasing the number in small steps. See what happens.

Do you have access to an oscilloscope? If so check the data into the second tile.

That’s what I thought about doing (using an oscilloscope) but I don’t have one at home, I could use the ones in school but due to corona, there are some strict rules. The first LED on the second matrix doesn’t light up, maybe that one is fried and broke the data line. I will check it out more thoroughly later. The code is from a simple example from neomatrix library.

// Adafruit_NeoMatrix example for tiled NeoPixel matrices.  Scrolls
// 'Howdy' across three 10x8 NeoPixel grids that were created using
// NeoPixel 60 LEDs per meter flex strip.

#include <Adafruit_GFX.h>
#include <Adafruit_NeoMatrix.h>
#include <Adafruit_NeoPixel.h>
#ifndef PSTR
 #define PSTR // Make Arduino Due happy
#endif

#define PIN 6

// MATRIX DECLARATION:
// Parameter 1 = width of EACH NEOPIXEL MATRIX (not total display)
// Parameter 2 = height of each matrix
// Parameter 3 = number of matrices arranged horizontally
// Parameter 4 = number of matrices arranged vertically
// Parameter 5 = pin number (most are valid)
// Parameter 6 = matrix layout flags, add together as needed:
//   NEO_MATRIX_TOP, NEO_MATRIX_BOTTOM, NEO_MATRIX_LEFT, NEO_MATRIX_RIGHT:
//     Position of the FIRST LED in the FIRST MATRIX; pick two, e.g.
//     NEO_MATRIX_TOP + NEO_MATRIX_LEFT for the top-left corner.
//   NEO_MATRIX_ROWS, NEO_MATRIX_COLUMNS: LEDs WITHIN EACH MATRIX are
//     arranged in horizontal rows or in vertical columns, respectively;
//     pick one or the other.
//   NEO_MATRIX_PROGRESSIVE, NEO_MATRIX_ZIGZAG: all rows/columns WITHIN
//     EACH MATRIX proceed in the same order, or alternate lines reverse
//     direction; pick one.
//   NEO_TILE_TOP, NEO_TILE_BOTTOM, NEO_TILE_LEFT, NEO_TILE_RIGHT:
//     Position of the FIRST MATRIX (tile) in the OVERALL DISPLAY; pick
//     two, e.g. NEO_TILE_TOP + NEO_TILE_LEFT for the top-left corner.
//   NEO_TILE_ROWS, NEO_TILE_COLUMNS: the matrices in the OVERALL DISPLAY
//     are arranged in horizontal rows or in vertical columns, respectively;
//     pick one or the other.
//   NEO_TILE_PROGRESSIVE, NEO_TILE_ZIGZAG: the ROWS/COLUMS OF MATRICES
//     (tiles) in the OVERALL DISPLAY proceed in the same order for every
//     line, or alternate lines reverse direction; pick one.  When using
//     zig-zag order, the orientation of the matrices in alternate rows
//     will be rotated 180 degrees (this is normal -- simplifies wiring).
//   See example below for these values in action.
// Parameter 7 = pixel type flags, add together as needed:
//   NEO_RGB     Pixels are wired for RGB bitstream (v1 pixels)
//   NEO_GRB     Pixels are wired for GRB bitstream (v2 pixels)
//   NEO_KHZ400  400 KHz bitstream (e.g. FLORA v1 pixels)
//   NEO_KHZ800  800 KHz bitstream (e.g. High Density LED strip)

// Example with three 10x8 matrices (created using NeoPixel flex strip --
// these grids are not a ready-made product).  In this application we'd
// like to arrange the three matrices side-by-side in a wide display.
// The first matrix (tile) will be at the left, and the first pixel within
// that matrix is at the top left.  The matrices use zig-zag line ordering.
// There's only one row here, so it doesn't matter if we declare it in row
// or column order.  The matrices use 800 KHz (v2) pixels that expect GRB
// color data.
Adafruit_NeoMatrix matrix = Adafruit_NeoMatrix(10, 8, 3, 1, PIN,
  NEO_TILE_TOP   + NEO_TILE_LEFT   + NEO_TILE_ROWS   + NEO_TILE_PROGRESSIVE +
  NEO_MATRIX_TOP + NEO_MATRIX_LEFT + NEO_MATRIX_COLUMNS + NEO_MATRIX_ZIGZAG,
  NEO_GRB + NEO_KHZ800);

const uint16_t colors[] = {
  matrix.Color(255, 0, 0), matrix.Color(0, 255, 0), matrix.Color(0, 0, 255) };

void setup() {
  matrix.begin();
  matrix.setTextWrap(false);
  matrix.setBrightness(40);
  matrix.setTextColor(colors[0]);
}

int x    = matrix.width();
int pass = 0;

void loop() {
  matrix.fillScreen(0);
  matrix.setCursor(x, 0);
  matrix.print(F("Howdy"));
  if(--x < -36) {
    x = matrix.width();
    if(++pass >= 3) pass = 0;
    matrix.setTextColor(colors[pass]);
  }
  matrix.show();
  delay(100);
}

The first LED on the second matrix doesn't light up, maybe that one is fried and broke the data line.

Swap the panels around, make the second, suspect panel, the first panel to see if it works or not. Make the first, good panel, the second panel.

Well it seems that the problem was that I was to blind to notice that my 8x led matrices were different 4 one kind 4 other kind although on the back of each one said it was the same model, but when you look carefully at the inside layout of the LEDs you can see the difference

How frustrating. Did you buy all of them at the same time?

Yes,I've bought them on the same order