Hi ,

Refer this to open form view on a button click

def action_view_invoice(self):
    return {
        'name': _('Customer Invoice'),
        'view_mode': 'form',
        'view_id': self.env.ref('account.view_move_form').id,
        'res_model': 'account.move',
        'context': "{'move_type':'out_invoice'}",
        'type': 'ir.actions.act_window',
        'res_id': self.account_move.id,
    }