[ERROR] [1556010329.448520]: Unable to sync with device; possible link problem or link software version mismatch such as hydro rosserial_python with groovy Arduino
Here you can find tutorial how publish data from CORE2 to ROS. But it use USB port instead of RPi connector. Your modification solving this problem.
ROSbot default firmware doesn’t work because you probably have these settings:
// Uncomment one of these lines, accordingly to range sensor type of your ROSbot
// If you have version with infared sensor:
// static const SensorType sensor_type = SENSOR_INFRARED;
// If you have version with laser sensor:
static const SensorType sensor_type = SENSOR_LASER;
// If you want to use your own sensor:
// static const SensorType sensor_type = NO_DISTANCE_SENSOR;
// Uncomment one of these lines, accordingly to IMU sensor type of your device
// If you have version with MPU9250:
static const ImuType imu_type = MPU9250;
// If you want to use your own sensor:
// static const ImuType imu_type = NO_IMU;
You probably don’t have IMU so program get stuck during IMU initialization.