It is easier to check for short circuits than open circuits. Just do as I say. It'll be easy to find.
1, as far as possible not to cut the line, first with the naked eye to see which place is easy to short circuit, and the component is easier to remove with the soldering iron, after finding, just remove the power pin, and then measure whether it is also short circuit, using this method to find where you think it is easy to short circuit;
2, the above method can not find, then cut line;
3, when cutting line, first choose the path, choose at the fork of a number of 12V power supply, such as from the fork into 1, 2, 3 roads, then cut off one of them, the total 12V is not a problem;
4, if after cutting off the line, there is no short circuit, then there is no short circuit before the cut point, you just need to check the line after the cut point to be able to (at this time to continue to cut and measure the line after the cut point); If the line behind the cut is still short, then the short circuit point is before the cut point, the next cut point should be selected in the previous line. In accordance with this method, you should soon be able to find the short circuit point, and then the cut point can be fully connected. Can you tell me about the cutting line skill? How to correct the position? Answer to the fault who can not be found under 1, as long as you press the above I tell you basically can quickly find the short circuit point. The key fault site may appear unexpected points, so the key your mentality should be flat, do not rush to tell you that I can find the problem. When cutting the line, the key is to cut at the fork so that it is easy to locate which 1 way, and cut in the place that is easy to repair, so that the problem can be found with the soldering iron 1 even without flying line.