@lost815execute besides all those great answers you already got, I swear by the right schematics and board layouts. It does not matter what make and model your phone is, unless you know what part you are looking at, it will be difficult to just replace. You can not distinguish if it is a capacitors, resistor, inductor etc. simply by looking at it. Same goes for troubleshooting. You do need to identify the individual circuits responsible for i.e. power up etc. Of course you do need the right tools. Multimeter, capacitance tester, etc. I use some ST5S smart tweezers to help me with the identification of the SMD components.
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=== Update (02/05/2017) ===
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As you commented to @theimedic if it is just an example about how to check a no power on situation, there are no standard answers. These are all model specific. Use a Samsung Wave schematic for example [image|1015255] and you'll see that is will only work for this model. You cannot use it for any other phone. There are not really any commonalities between cellphones on a circuitry level.
@lost815execute besides all those great answers you already got, I swear by the right schematics and board layouts. It does not matter what make and model your phone is, unless you know what part you are looking at, it will be difficult to just replace. You can not distinguish if it is a capacitors, resistor, inductor etc. simply by looking at it. Same goes for troubleshooting. You do need to identify the individual circuits responsible for i.e. power up etc. Of course you do need the right tools. Multimeter, capacitance tester, etc. I use some ST5S smart tweezers to help me with the identification of the SMD components.