A. 1. Force close the app: Double-click the Home button (or swipe up from the bottom of the screen on iPhones without a Home button) to view all open apps. Swipe up on the stc pay app to close it. Then, try reopening the app.
B. 2. Restart your iPhone: Press and hold the power button until you see the 'slide to power off' option. Slide to turn off your device, wait a few seconds, and then turn it back on. This can help clear temporary glitches.