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.

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).

The technician will check the production date codes and brand logos in the lower left corner of all the car's glass (including the windshield, four doors, and rear window) to see if they match the vehicle's factory date on the nameplate. If any glass is found to have a date later than the vehicle's production date, it will be recorded as evidence of a "previous damage replacement."