Android Flash

• Connect Charger and check phone for charging many time user doesnt check if phone display charging means there is problem with on/off switch or the track of power switch is open some time this problem can be rectified by changing power button or applying jumper if the track is open.
• Check the battery terminals clean properly and also check battery points some time due to carbon the connection between battery and motherboard cant be done so phone doesnt ON.
• Resold the battery connector.
• 50% of dead phone can be recovered by above method if not succeed then use the dc power supply (you can also use phone battery to check) after giving power to motherboard now place your multimeter in dc voltage measurement mode (knob should be placed at 10/20) and check the voltage at positive terminal of on/off switch. 

Voltage Measurement     

• place black prob on ground and red prob on +ve pin of power button
• You will get voltage approx 3volt ( voltage may differ according to models and brands) 
• Now press the power switch the volt will drop and show zero 0 volt.
• then voltage will exceed and will go approx 3.7 volt. (this is normal case and in this case your phone is in on condition) 
• After placing prob if we dont get the voltage at +ve arm 
• check Power IC 
• First clean the PCB.
• Put some soldering paste under and above Power IC and rehot the IC.
• If not succeed reball the Power IC
• Change Power IC.
• If we get some voltage and after switching again we get same voltage 
• This is mostly due to Software problem
• Connect your phone to computer and flash the firmware.
• Some time due to dry Soldering of power IC and CPU it may not connect to the computer in this case clean the whole PCB properly and rehot it. and check phone before flashing.
• If after rehot CPU and Power IC phone is dead condition then apply Software (flashing).