Unexpected battery drain
Phone overheating when not in use
Unusual data usage spikes
Random pop-ups or ads
Apps you did not install
Strange background activity
Calls or texts you did not send
Delayed shutdown or startup
Microphone or camera activating unexpectedly
Location sharing turned on without your consent
Account logins from unknown devices
Security settings changed without your knowledge
Poor performance or frequent crashes
Unknown Bluetooth or Wi-Fi connections
Friends receiving odd messages from you
SIM card or service issues without explanation