How to verify PayPal Webhook signature?

Having trouble validating the Webhook received from PayPal. Not many examples are available and not enough knowledge about encryption is possessed by the integrator to accomplish the task.

The guide being followed is Webhook notifications.

Not sure what is wrong with the code snippet, the result is always false.

Calling notifications/verify-webhook-signature endpoint is also resulting in false.

        /// <summary>Verify PayPal Webhook Signature</summary>
        /// <param name="webhookId">0YF54686R9851380C</param>
        /// <param name="transmissionId">785bc690-901d-11ea-8fc5-17f05150a6df</param>
        /// <param name="transmissionTime">2020-05-07T04:44:33Z</param>
        /// <param name="certUrl">https://api.sandbox.paypal.com/v1/notifications/certs/CERT-.....</param>
        /// <param name="transmissionSignature"></param>
        /// <param name="webHookEvent">"{\"id\":\"WH-5P8216093E7920426-60J97470GW748563B\",\"create_time\":\"2020-05-07T11:43:48.000Z\",....</param>
        private static void VerifyWebhookSignature(string webhookId, string transmissionId, string transmissionTime,
            string certUrl, string transmissionSignature, string webHookEvent)
        {
            Crc32 crc32 = new Crc32();
            String hash = string.Empty;

            var arrayOfBytes = Encoding.UTF8.GetBytes(webHookEvent);
            foreach (byte b in crc32.ComputeHash(arrayOfBytes)) hash += b.ToString("x2").ToLower();

            string expectedSignature = String.Format("{0}|{1}|{2}|{3}", transmissionId,
                transmissionTime, webhookId, hash);

            string certData = new System.Net.WebClient().DownloadString(certUrl);
            X509Certificate2 cert = new X509Certificate2(Encoding.UTF8.GetBytes(certData));

            try
            {
                byte[] signature = Convert.FromBase64String(transmissionSignature);
                byte[] expectedBytes = Encoding.UTF8.GetBytes(expectedSignature);

                using (RSA rsa = cert.GetRSAPublicKey())
                {
                    var verified = rsa.VerifyData(
                        expectedBytes,
                        signature,
                        HashAlgorithmName.SHA256,
                        RSASignaturePadding.Pkcs1);

                    Console.WriteLine($"Verified: {verified}");
                }
            }
            catch (Exception ex)
            {
                throw;
            }
        }