Check for sudden battery drain
Check for unusual data usage
Check for overheating when idle
Check for unknown apps installed
Check for apps requesting suspicious permissions
Check for pop-ups or ads outside the browser
Check for frequent crashes or freezing
Check for unexplained reboots
Check for calls or texts you did not send
Check for contacts you did not save
Check for login alerts from your accounts
Check for password changes you did not make
Check for unknown devices signed into your accounts
Check for microphone or camera indicators activating unexpectedly
Check for settings changed without your action
Check for browser redirects or homepage changes
Check for disabled security features
Check for high background activity in battery or data settings
Check for SMS messages with strange links or codes
Check for unfamiliar VPNs, profiles, or device admin apps
Check for bank or email account activity you do not recognize