Hi ,

To achieve this you can super the function of the validate button and can add the validations.

class AccountInvoiceInherit(models.Model):
    _inherit = 'account.invoice'
    
    @api.multi
    def action_invoice_open(self, vals):
        # check here and add the validations
        res = super(AccountInvoiceInherit, self).action_invoice_open(vals)
        return res