The main Raspberry Pi faults and troubleshooting methods are often related to power supply problems or improper operation of the device when powered on. A quality power supply is the main factor that ensures stable operation of the board and absence of many problems. If the red light on the device is not lit and there is no image on the screen, most likely the device is simply not getting power and you need to check the power supply. Sometimes the red LED may blink, which is usually due to insufficient voltage – in this case it is recommended to replace the power supply with a more powerful and better quality one. If the red LED is on but the green LED is not blinking and no image appears, it is likely that Raspberry Pi cannot find the operating system image on the memory card. It is necessary to make sure that the memory card is correctly inserted and the OS image is correctly written on it, as well as to check its compatibility. Sometimes it helps to disconnect all cables except power supply and connect the others one by one to find the problem device.
It’s also worth checking the SD card contacts, as poor contact can prevent downloading. The contacts should be well sprung and protrude to the correct length – sometimes gently adjusting their position can help. If the green light flashes a certain number of times, this indicates specific bootloader errors or corruption of key system files that may need to be replaced. The appearance of a multicolored square on the screen usually signals problems with loading the system kernel. In such cases, it is worth replacing the relevant file or checking the power quality, as lack of power can lead to reboots.
The Kernel Panic error, when the boot stops with the corresponding message, is most often associated with incompatible USB devices, such as keyboards. Disabling these devices sometimes solves the problem. If the Raspberry Pi reboots immediately after startup, most likely the cause is again due to insufficient power. Sometimes the device boots unstably when the power supply and SD-card are intact, which is associated with overheating or counterfeit memory cards. SD-card contacts in such cases should also be rechecked.
Keyboard and mouse problems are often power related too. Some USB devices require much more power than the Raspberry Pi can provide without an external USB hub with its own power supply. In some cases, simultaneous use of wireless keyboards and USB WiFi adapters causes failures due to differences in data transfer rates. This can be solved by selecting a high-quality power supply unit and thinking over the connection scheme of the devices.
Not all wireless keyboards are compatible with Raspberry Pi, so you should check their support before buying. Sometimes characters entered from the keyboard do not match the symbols on the keys – for this you need to change the keyboard layout in the system settings. If after the changes Raspberry Pi takes longer to boot, you can use special commands to speed up the setup.
Sometimes USB devices don’t work at all, although everything seems to be in good working order. In such cases the reason may be the lack of clock signal on the USB/Ethernet controller. Sometimes re-soldering of the corresponding generator helps, but most often the problems are related to insufficient power supply or incompatibility of the equipment. It should be remembered that factory defects are extremely rare and are usually not the cause of problems.