Check if the phone if it's turning on/off, check the number keys, check if all the keys are usable, check if the receive/disconnect button are working, check the reboot time, check the company logo n its animation, check if the display is fine, check if the screen gets flickered while scrolling, check if all the inbuilt apps are present, check if the screen is scrolling, check if the scrolling is lagging or smooth, check if the phone gets heated, check if the phone gets lagged on opening multiple apps, check If all the slots (earphone, charger, Sim, memory card) are working fine.