Use a fixed string for secretKey to replace random genereated 20 length string.

 'Dim mySecretKey As String = Me.GenerateRandomKey(20)
 Dim mySecretKey As String = "JBSWY3DPEHPK3PXP"

Using random secretkey causing QR code added account is not reusable. Therefore, we need to scan the QR code every time at the OTP validation step.