customPanel.close()

await customPanel.close();

const customPanel = instance.customPanels.getPanel();

customPanel.hostElement.innerHTML = `
  <div style="padding: 16px;">
    <p>Please confirm your one-time password to proceed.</p>
    <input id="otp-input" type="text" placeholder="Enter OTP" />
    <button id="confirm-btn">Confirm</button>
  </div>
`;

document.getElementById('confirm-btn').addEventListener('click', async () => {
  const otp = document.getElementById('otp-input').value;
  // Validate OTP...
  await customPanel.close();
});

await customPanel.open({ title: 'Confirm Payment', hideBackButton: true });