Please first confirm the specific issue you are facing:
1. If the blade holder does not go down during cutting
This is usually caused by a mainboard malfunction.
In this case, the solution is to replace the mainboard.
2. For other carriage-related failures
If the issue is not about the blade holder failing to drop, then the entire cutting car assembly may be faulty.
Please replace the whole carriage.
You can follow the step-by-step replacement method shown in the video below.