We use two steps: 1. Insert a medical-grade endoscope through the spark plug hole to visually inspect cylinder wall scratches and carbon buildup on the piston top; 2. Extract an engine oil sample to check for large metal debris or emulsification (caused by coolant leakage).

Once the car system (especially in a closed ecosystem) undergoes a major version upgrade, its bootloader is usually locked, preventing downgrades. If this happens, there is basically no solution in an overseas environment. Therefore, we strongly warn: do not blindly insert a USB drive to upgrade while offline.

Under normal circumstances, it takes 15 to 25 working days. This includes: domestic transfer of ownership (3-5 days), applying for an export license (3-5 days), inland trucking to the port (2-5 days), customs inspection and waiting for loading schedule (5-10 days). Do not trust false promises from other channels claiming 'loading within a week.'