When the GUI tells you that it is focusing, that is just their abstract term for the entire initialization process. Your particular GF is never making it to the actual focusing routine as it is experiencing a problem during the hardware initialization.
Specifically, it appears that the control board is not able to establish I2C bus communications with the head.
Relevant parts of
2019-12-31_03:00:43.89880 8196 DEBUG: head_accel_abort: setting to 0
2019-12-31_03:00:43.89881 8196 ERROR: i2c_transfer: ioctl failed (9: Bad file descriptor, src/i2c.cpp:26)
2019-12-31_03:00:45.73493 10034 ERROR: i2c_transfer: ioctl failed (9: Bad file descriptor, src/i2c.cpp:26)
2019-12-31_03:00:45.74710 10040 ERROR: fused_temp: could not read head temp sensor (src/sensor_task_peripherals.cpp:397)
The lid, head, and accessory boards all have their own distinct I2C buses, and the errors indicate that the lid and accessory board buses may be working properly. The head bus is not.
The head I2C utilizes PCA9600 bus extenders (datasheet) - there is one on the GF head board (U19) and the GF control board (U40). These convert the 3.3 VDC I2C bus signals to 12 VDC for transport over the wires between boards, and back to 3.3 VDC.
You can see the basic circuit for this in the OpenGlow schematic, sheet 4, grid A5. (Note: This is the schematic for the OpenGlow, NOT the GF, but the bus extender circuits are essentially identical)
All this being said, my first suggestion would be that you check that the head connector is OK. The pins have a tendency to get bent. Make sure to check, and re-seat, both ends of the flat cable - the one on the head board (J2), and the one on the accessory board (J1).
If those are good to go, the next step would be troubleshooting the operation of the electronics.