A technician is investigating an employee's smartphone that has following symptoms: The device is hot, even when it is not in use. Applications crash, especially when others are launched. Certain…

The symptom of certain applications being stuck in portrait mode when they should be in landscape mode directly points to the autorotation feature being disabled or malfunctioning. Enabling it would resolve this specific issue.

Activating airplane mode disables all wireless communications and would prevent the phone from functioning normally, which is not a general troubleshooting step for these issues.

A hot device and crashing applications often indicate excessive resource usage by background processes or too many applications running simultaneously. Closing unnecessary applications can free up resources, reduce CPU load, and lower the device's temperature.

Performing a factory reset is a drastic measure that erases all user data and settings; it should be considered only after less impactful solutions have failed.

While updating the OS is generally good practice, it's not the first step for these specific symptoms as it might not be a direct cause and could be more impactful if not smooth.

Reinstalling only the crashed applications might address issues with those specific apps but won't resolve the general device overheating or other app crashes, especially if the root cause is system resource contention.