There are many reasons why a mobile phone is charged but cannot be turned on! Here to give you a detailed list of several, I hope to help you!
1, the boot line is not normal to see: use the external power supply to power the phone, use the power meter test to see if there is a change in the number, if there is no change, it is likely that the boot line is broken or the boot key contact is poor.
2, the power supply circuit of the battery is abnormal: use the external interface to power the phone, see when the boot is restored to normal, if normal, it is determined that the power supply circuit of the phone is abnormal.
3, the IC of the mobile phone power supply is abnormal: test on the test point of the outer circuit of the power supply IC against the circuit schematic to see whether the test value is normal.
4, the system clock and reset of the mobile phone is abnormal: you can use the dual oscilloscope to detect the CPU power supply of the mobile phone to check whether the waveform diagram in the reset is correct.
5, the logic circuit problem: that is, the fault of the mobile phone circuit version, generally can be solved by repairing welding.
6, software conflict: the installed software and the mobile phone system does not match may also cause the phone can not turn on the situation, you can connect the phone to the computer to delete the program.
7, if it is a cottage mobile phone, then I estimate that I can not open the machine because the chip inside burned, or some of the small parts inside loose, but this situation is that you will appear, the chip burned may be you charge for too long, the chip burned, if the battery has power, it is these aspects, if it is a brand-name mobile phone, such as Nokia, MOTOROLA....... These cases are very rare, unless it is artificial, if it is a brand-name smart phone, and not improper use, play is a software problem, there may be a system crash, or because of mobile phone poisoning caused by software damage, generally only to the repair, however, I think the biggest may be caused by static electricity, it is recommended that you do not open blind repair. It's better to go to the maintenance office.