After invoice has been revalidated, the status of it become Selected for Validation and partial acco

The invoice was paid for full amount XXX. But after paid , I adjusted Item XXX to VAT XXX. But not lucky, after I corrected invoice XXX, this invoice cannot be validated. The status for this invoice is selected for validation, so I cannot change any data for this invoice anymore and this invoice was partial accounted at the same time. 

 

 As for accounting for VAT line of XXX (it has been accounted) so I need to reverse this VAT line.