How to Fix MacBook Pro Won't Turn On Issue？

Users tend to get frustrated when their MacBook Pro encounters startup issues.The problem is especially annoying when there is a large amount of data storage or a large number of important files.There are various reasons for this situation,which may be related to conflicting startup settings of some third-party apps,or there may be a problem with the account associated with the Mac.If you encounter the same problem,here are some basic troubleshooting methods to help you solve the‘MacBook Pro won't turn on’problem.

　　Firstly,try connecting your MacBook Pro to a power source via the Apple Lightning Cable and press the power button to see if it powers on normally.If the screen is still black and unresponsive,then you need to disconnect the power and open the laptop using the JM-P01 kit.Next,remove the back case and battery and carefully remove the motherboard in order to check for any burning smell.

　　During the removal process,you can smell a burning odour,indicating that a component may have been damaged.At this point,it is necessary to locate the damaged components and place the MacBook Pro motherboard on the WL aluminium pad.

　　Looking at the schematic and PCB bitmap,it was found that there is a compound diode D6905 which is used to generate PP3V3_G3H i.e.the first 3.3V power supply.Based on the MacBook schematic,we know that the L6995 inductor is associated with this circuit.

　　Using a Fluke 17B+digital multimeter to measure inductor L6995,the test value is 342,which is within the normal range.

　　Next,we need to measure the inductor D6905,there are three pins to be measured,pin 1,pin 2 and pin 3.after measurement,we found that only the value of pin 2 is tested normal,while the value of pin 1 and pin 3 are not normal.the value of pin 1 is tested as 97,while the value of pin 3 is tested as 0,which indicates short circuit.

　　So,based on the above information,we can conclude that the MacBookPro won't power on issue is due to the damage of a certain compound diode D6905.In order to fix this issue,you may need to replace the D6905 diode with a new one.Make sure you know your MacBookPro model number as well as the relevant hardware components before performing any repairs to avoid further damage.