Hi

    <record id="view_invoice_customer_1" model="ir.ui.view">
        <field name="name">account.invoice.customer.test</field>
        <field name="model">account.invoice</field>
        <field name="inherit_id" ref="account_voucher.view_invoice_customer"/>
        <field name="arch" type="xml">
            <xpath expr="//button[@name='invoice_pay_customer']" position="replace">
                <button name="invoice_pay_customer" type="object" string="Register Payment"
                    attrs="{'invisible': ['|', ('state','!=','open'), ('sent','=',True)]}" groups="base.group_user" invisible="1"/>

            </xpath>
        </field>
    </record>

hope this will help you