The trunk of the Big Dipper can't be lifted.

Bolt failure, sealing ring replacement failure, spring failure, buffer block failure.

1. First, the bolt is faulty. Solution: Adjust the bolt. When closing the trunk, the bolt position of the original car changed slightly due to excessive pressure, which led to the situation that it could not be supported, so it was necessary to adjust the bolt to the correct position.

2. Secondly, replace the sealing ring. Solution: Replace the sealing ring. If it is used for a long time, it may lead to the aging of the sealing ring, so it is necessary to replace the aging sealing ring.

3. Then, the spring fails. Solution: Adjust the spring. The new car will adjust the tension spring to the first position. After a long time, the resilience of the spring will weaken, and it is necessary to adjust the spring to the second position.

4. Finally, the buffer block fails. Solution: Adjust the buffer block. It may be caused by the loosening of the torsion bar in the trunk, which can be solved by adjusting the buffer block in the trunk.