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).

Maintain objective expectations. Vehicles over 5 years old inevitably show signs of decreased paint gloss, slight aging of rubber seals, irreversible patina on interiors, and surface rust on chassis components. As long as core structure and mechanical failures are not involved, these are normal depreciation characteristics over time.

This is a typical case of "secondary damage caused by unprofessional rescue." Many hybrid vehicles require access to "maintenance mode" via engineering computers to allow the water pump to run at full speed for exhaust. We do not bear any moral or financial responsibility for cylinder damage caused by local technicians' misoperation.