Did you try the Norton Account password instead of the vault password? This is what I had to do earlier today.
If that is accepted, you may be able to tap on PIN again and use it.
Either way, you will have to find a way to get the vault password or you are going to lose all your logins. One thing to check on your desktop. Look in Windows File Explorer in your Documents folder. See if you have a folder Norton Identity Safe Backups. In that folder will be another folder with your email address. In that folder will be backups of your vault. If you cannot get back into your vault, we can use this to reset your vault.
I only entered the incorrect PIN once before it then prompted for the password. On the screen it has the PIN on one side and the Password on the other. It immediately move over the password. I thought it was a slider at first which allowed you to choose one or the other but it won't move over nor can I select the PIN option again. I'm essentially stuck at password.
I'm still logged into Identity Safe but since I don't know my password I can't open the vault. I'm not sure what options I have left though. It also prompts for the password if I try from a desktop. I have a bad feeling about this since all my password are stored in the vault an nowhere else.
I have not used the PIN feature, so I just set it up on my test device. It appears you have to enter the incorrect PIN about 5 times before it is disabled.
Are you sure it was not just asking for the Norton Account password? I find that the ID Safe on Android occasionally 'expires' the login to the Norton Account. In fact I saw this just now when I logged in to try the PIN function.