My document has a closed padlock next the document name. How to unlock my document?

The root cause is because the Production Package and /or the JSON files now they have the Approve for Use status. Review the status going to Relationships > Components and check the status of assembler.project.json and the ProductionPackage <document number>

Move components to draft

In order to update Approved For Use components, you can move them to draft, make the necessary change and then get them reapproved. Please be aware that this action can affect all materials using this component. You should be certain you are aware of the impacts of this change before doing so.

To move an Approved For Use component to Draft, the user should open the component’s placeholder and click on the actions menu. In the dropdown menu, the user should click on “Create Draft”. After clicking on “Create” in the pop-up, the placeholder will refresh and it will now be in Draft status.

To know more about the approval process for the components, check this article.