Edit PO Header Text after the PO is blocked

Hi Experts,

The user wants to edit the PO header Text after the PO is blocked. i.e, he selects an approver after entering all the details and submit for approval. After this the PO is saved and when he opens the PO next time in ME22N, all the fields are disabled.

Is there a possibility where we can still edit the header text through any configuration / customization?

Thanks,

Ajith