Check for unusual battery drain
Check for unexpected data usage spikes
Check for overheating when idle
Check for random pop-ups or ads
Check for apps you did not install
Check for unknown device administrator apps
Check for unfamiliar permissions granted to apps
Check for calls, texts, or emails you did not send
Check for strange account activity
Check for login alerts from your accounts
Check for phone performance slowing down suddenly
Check for apps crashing or opening by themselves
Check for settings changing without your action
Check for microphone, camera, or location indicators appearing unexpectedly
Check for unknown charges on your bill
Check for forwarding rules on calls, texts, or email
Check for browser redirects or homepage changes
Check for security warnings from antivirus or system tools
Check for rooting or jailbreaking you did not do
Check for unknown Bluetooth or Wi-Fi connections
Check for suspicious SMS messages with links or codes