There are many components inside a modern smartphone that is not only a miniature computer with memory, RAM and processor, but also has sensors, microphone, speakers, radio for bluetooth reception, wifi, gps and many other things. If something does not work well, there may be a problem on the software side (i.e. operating system or app) or that, on the hardware side, one of the internal components is defective. To check for any problems, to find out if there is any faulty piece or if there is a wrong system configuration, there are some Android applications that can help us.
1) One of these applications is provided by Google and is called Device Assistance, available on the Google Play Store only for Nexus or Moto G smartphones (it has now been withdrawn).
For all other phones you will need to install it by downloading the Application Support APK file.
This application is basically an interactive guide to discover all the functions of the phone with tips and advice on how to best use an Android smartphone. Recommendations also include reports of any problems and how to correct them by changing a system setting. There are also some tests such as the one on the screen and that of the wifi. Everything is written very clearly in Italian, making it an excellent assistant especially for beginners.
2) Test Your Android is instead an app that allows you to check if all the hardware components are intact and are working well. You can therefore check the proper functioning of the speakers, the screen, the camera, the light sensors, the accelerometer, the proximity, the GPS, Wifi, Bluetooth receivers. You can also check the processor speed and see all the hardware information for the smartphone (CPU, memory, battery, internal space etc.).
3) Phone Doctor is an app that would like to be an automatic repairer of any cellphone problems. For example, if the microphone does not seem to work well or if the sound of the speakers is low, it may be possible to solve the problem with Phone Doctor (provided that the speakers are not damaged). You can then do various "stress tests" on sensors and functions of the mobile phone and check the health of the various components such as the CPU and the battery.
4) Z-Device Test is an app that I have already mentioned in the article on how to do hardware tests on Android, excellent and complete to check the correct functioning of every part of the smartphone, especially the sensors.
5) Repair battery life is an app to check all the battery cells and check that they are healthy and actually recharge. You can then try to repair inactive or low-recharge cells. I can't say if this app is telling the truth, even if from the comments it seems to be really effective.
6) Dead Pixel Fixer is used to fix dead or defective pixels on the screen. With Android test you can check if the screen pixels are all intact but nothing can be done to repair them. With this app, on the other hand, it is possible to unlock the pixels that have remained still on a color.
Without installing the app, you can also try connecting to the JScreenFix website, which works even better than the application, to repair broken Pixels of any LCD screen.
7) Speaker Test allows you to check if the speakers work well to their full capacity. With frequency tests, it is also capable of unlocking the speakers if they are left with too low a volume.
8) Ampere to check if the smartphone is charging correctly is an app to have absolutely, also to measure the integrity of the charging cables and transformers in use.
9) GPS Fix to improve GPS reception, very useful on smartphone phones that have difficulty finding satellites quickly when opening the GPS navigator.
10) CPU Z, Antutu and Android benchmarking and hardware comparison app to check the processor and know how good it is even compared to that of other smartphone models.
11) Accubattery for the health of the battery is the absolute best for measuring its capacity.
12) TOuch Screen Test to calibrate the touchscreen of the Android smartphone, explained in another post.
When you bring a phone to service in case something is not working well, if the phone technicians know some secret codes and menus that allow you to test and check what is actually wrong
