# TRB-2: Mobile OS and App Issues

Status: not started

Domain:
- 3.0 Software Troubleshooting

Objective alignment:
- 3.2 Troubleshoot common mobile OS and application problems

## What You Need To Know

Mobile troubleshooting often starts with simple checks:
- Updates
- Storage
- Permissions
- Connectivity
- App cache/data
- Battery health
- Compatibility

Common symptoms:
- App fails to launch
- App fails to close
- App fails to update
- App fails to install
- App crashes
- Slow response
- OS update failure
- Battery drain
- Random reboots
- Bluetooth, Wi-Fi, or NFC problems
- Screen autorotation failure

## Memory Trick

Use **U-S-P-C-R**:

- **U**pdate
- **S**torage
- **P**ermissions
- **C**onnectivity
- **R**estart/reinstall

Shortcut:
- **Most mobile app problems start with update, storage, permission, or connectivity checks.**

## Troubleshooting Flow

App will not launch or crashes:
- Restart the app.
- Restart the device.
- Update the app.
- Update the OS.
- Clear app cache where supported.
- Reinstall the app if needed.

App will not install or update:
- Check storage.
- Check network connectivity.
- Check app store account status.
- Check OS compatibility.

Battery drains quickly:
- Review battery usage by app.
- Check screen brightness.
- Disable unnecessary radios.
- Check for runaway apps.

Connectivity problems:
- Toggle the affected radio.
- Forget and reconnect to the network or device.
- Check range and pairing mode.
- Restart device if needed.

Autorotation fails:
- Check rotation lock.
- Restart the app.
- Test sensors if available.

## Exam Clues

- If an app cannot install, storage and compatibility are high-probability answers.
- If Bluetooth pairing fails, check pairing mode and forget/re-pair.
- If the issue started after an update, check known issues and compatibility.
- If one app is the only problem, focus on that app before resetting the whole phone.