Not exactly a beginner at soldering and rather experienced with Arduino / Edison stuff.
From what I can see your soldering looks good. If you're familiar with Arduino and have it installed on your computer you can try seeing if you can read the magnetometer via the Arduino IDE's serial monitor window. To do this shut down the EDTracker GUI if you still have it open and then open up the Arduino IDE. Under the 'Tools' menu set the COM port to whatever the EDTracker is using. Then open a serial monitor window and set its baudrate to 115200. You should then be able to read the magnetometer by sending a capital 'I' to the EDTracker. The EDTracker should then return a magnetometer reading.
If this doesn't work and you don't mind having a go at reprogramming the Pro Micro you could try the MPU9250 test sketch. This will at least determine if the Pro Micro is talking to the MPU9250. If you want to give it a try you'll first need to add support for the EDTracker to your Arduino IDE. To do this follow steps 1 to 5 in the following post:
viewtopic.php?p=7990#p7990
When you've added board support you can try the MPU9250 test sketch found in the first post in the MPU9250 product thread here:
viewtopic.php?f=73&t=1956
When uploaded, the sketch will output the state from all the MPU9250 sensors to the Arduino IDEs monitor window (note the sketch uses a baud rate of 9600). See if the values change when you move the EDtracker.
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