I can offer you some hints to help in your search why the fuse blew.
If you look at the schematic for Carloop, it has only 5 connections through the OBD connector:
- Chassis GND
- Signal GND
- CAN Hi
- CAN Lo
Ground faults do not blow fuses.
The CAN Hi & Lo are differential signalling lines, so I seriously doubt that would cause any fuse to blow, even if there was a fault.
That only leaves the 12V. To check this, I would suggest connecting your Carloop to a lab power supply with current control, and check that the power draw is within specifications.
Another thing you might check is to remove the Photon/Electron/RedBear Duo and check that your microcontroller is drawing proper power.
The other thing that is necessary is to get an electrical diagram for the car. Is the OBD port on the same circuit as the engine SOL fuse? If not, then it must be something else. If it is, what is the existing load on the circuit, and is there (a small) capacity available to run Carloop? Is the voltage okay in your car? Voltages are usually about 13.5V in order to charge the battery. A much higher voltage might be a sign that the alternator or voltage regulator inside the alternator could be a problem.
Post any further questions and how your investigation is going!