INV: How to go backwards and fix items mistakenly invoiced (ADVANCED)

OVERVIEW:

Sometimes we have to fix up mistakes that slip through and get invoiced for what ever reason. Here are some step by step instructions on how to do this. There are TWO scenarios to follow, choose the ONE that relates to you.

SCENARIO 1 - Invoice has been synced across to accounting system and approved

SCENARIO 2 - Invoice was NOT sent or synced across to accounting system OR wasn't approved and deleted out of accounting system

SCENARIO 1:

1. In the invoice list do a credit for the invoice that was incorrect and sync across to the accounting system (if you haven't already done this in your accounting system).
2. Edit the incorrect invoice and change the Status to Auto Generated so it "unlocks" the invoice - you need to do this to be able to UN-INVOICE in the Pre-Invoicing (WIP) list.
3. In the Pre-Invoicing (WIP) list select the lines/items/charges that you wish to UN-INVOICE and then click UN-INVOICE button that appears at the top of the screen. If all you needed to do is un-invoice because they shouldn't have been charged yet then do step 4 and stop there.
4. Go back to the invoice list and edit the invoice to "lock" it by changing the status to Draft to Accounting.
5. In the Pre-Invoicing (WIP) list make what ever corrections that need to be made to the charge lines. 
6. Once you're happy with the pre-invoicing lines then you can INVOICE them. This will create a NEW invoice for you to send and sync.

SCENARIO 2:

1. Make sure the invoice is DELETED out of the drafts folder in your accounting system.
2. (If the invoice has been sent or synced do this step) In the Invoice List, Edit the incorrect invoice and change the Status to Auto Generated so it "unlocks" the invoice - you need to do this to be able to UN-INVOICE in the Pre-Invoicing (WIP) list.
3. In the Pre-Invoicing (WIP) list select the lines/items/charges that you wish to UN-INVOICE and then click UN-INVOICE button that appears at the top of the screen. This will reverse the selected charges back out from the invoice. If all you needed to do is un-invoice those items (and left some charges in the invoice) because they shouldn't have been charged yet, then do step 4 and stop there. If you need to edit the charges and re-invoice skip to step 5.
4. Go back to the Invoice List and send/sync your invoice (Remember, it must first be deleted out of the Draft folder in your accounting system).
5. In the Pre-Invoicing (WIP) list make what ever corrections that need to be made to the charge lines. 
6. Once you're happy with the pre-invoicing lines then you can INVOICE them. This will put the new/corrected charges into the same invoice as before.
7. Go back to the Invoice List and send/sync your invoice (Remember, it must first be deleted out of the Draft folder in your accounting system).