Firstly, I need to validate the serial numbers put in by users to make sure it is correct with what is already in database. However, I noticed even if the wrong serial number is inputed, the page reloads (shows the error message) and still fills in the wrong serial number in the field cf_954. So whether it is wrong or right, the field still gets populated.

Secondly, i noticed that the alert script only shows in mobile not on desktop browser.

<?php

/*** 
This code was rewritten by Peter Iteka 
The Original code is placed in Root dir as OLD CODES
*****/

// Enable error reporting for debugging purposes
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL & ~E_NOTICE & ~E_DEPRECATED);

function Jobs_DeliverBinDelivered_field_Workflow($entity) {
    global $current_user, $adb, $log;

    // Prevent any output before the JSON response
    if (ob_get_length()) ob_end_clean(); // Ensure any prior output buffer is cleaned.

    // Include necessary vtiger utility files
    include_once 'include/utils/CommonUtils.php';
    include_once 'include/database/PearDatabase.php';

    // Extract the entity ID
    $id = explode("x", $entity->get('id'));
    if (count($id) < 2) {
        error_log("Invalid entity ID format.");
        return;
    }
    $potid = $id[1];

    // Ensure required fields are set
    if (!isset($entity->data['cf_accounts_id']) || !isset($entity->data['cf_954'])) {
        error_log("Required fields are missing in the entity data.");
        return;
    }

    // Retrieve field values
    $acc_id = explode("x", $entity->data['cf_accounts_id']);
    if (count($acc_id) < 2) {
        error_log("Invalid cf_accounts_id format.");
        return;
    }
    $accounts_id = $acc_id[1];
    $serialnumber = $entity->data['cf_954'];

    // Define an array of valid product IDs
    $valid_products = [
        6570, 6569, 6571, 6574, 6575, 6576, 6577, 6578, 6580, 6588, 
        6589, 6591, 6593, 6598, 6603, 6605, 6610, 6611, 6628, 6634, 
        6637, 7065, 7479, 11047, 11061, 11196, 12518, 20067, 20210, 
        30015, 51241, 60124, 60546, 63629, 72512, 72513, 72596, 77932, 
        77944, 78159, 79504, 80215, 107739, 132729, 144886, 148546, 
        149185, 152960, 156049, 156354, 160736, 160737
    ];

    // Prepare and execute the SQL query to find assets with the given serial number and a valid product
    $sql = "SELECT * FROM `vtiger_assets` WHERE `serialnumber` = ? AND `product` IN (" . implode(',', $valid_products) . ")";
    $result = $adb->pquery($sql, array($serialnumber));

    if ($result === false) {
        error_log("Database query failed: " . $adb->database->ErrorMsg());
        return;
    }

    $row_find_count = $adb->num_rows($result);

    function phpAlert($msg) {
        echo '<script type="text/javascript">
                alert("' . $msg . '");
                window.location.reload();
              </script>';
    }

    // If no assets are found, reject the serial number and return a JSON error message
    if ($row_find_count == 0) {
        // Log error for internal purposes
        error_log("Invalid serial number: $serialnumber or product mismatch. Contact the office for assistance.");

        // Show an alert to the user
        phpAlert("Invalid serial number or Bin number mismatch. Input the correct one or call the office. Thank you.");

        // Ensure that the response is sent and the connection is closed
        die();
        flush();
        exit(); // Prevent further execution
    }

    // If assets are found, proceed with updating them
    $ACC_ID = array();
    for ($i = 0; $i < $row_find_count; $i++) {
        $ACC_ID[] = $adb->query_result($result, $i, 'assetsid');
    }

    // Update each found asset record with the new account ID
    foreach ($ACC_ID as $row_id) {
        $recordModel = Vtiger_Record_Model::getInstanceById($row_id, 'Assets');
        if ($recordModel) {
            $recordModel->set('account', $accounts_id);
            $recordModel->set('mode', 'edit');
            $recordModel->save();
        } else {
            error_log("Failed to load record model for assetsid: " . $row_id);
        }
    }
}
?>

Used this function to stop the code from running

  if ($row_find_count == 0) {
        // Log error for internal purposes
        error_log("Invalid serial number: $serialnumber or product mismatch. Contact the office for assistance.");

        // Show an alert to the user
        phpAlert("Invalid serial number or Bin number mismatch. Input the correct one or call the office. Thank you.");

        // Ensure that the response is sent and the connection is closed
        die();
        flush();
        exit(); // Prevent further execution
    }