Why does the battery have no output

When receiving feedback from customers that the cylindrical 18650 lithium battery pack cannot be charged or has no output (for example, the analysis of the lithium battery pack is Sanyo 18650, 11.1V lithium battery pack), the battery is now confirmed, tested and analyzed as follows:
1), confirm the battery production date;
2) Use a multimeter to detect the voltage of the battery pack and the output voltage is 0V;
3), use the DC source to detect the battery charging function, there is no response;
Remarks: If the voltage of the cell is too low, and there is no output voltage after the low-voltage protection of the protection board, it can be activated by charging;
4) Disassemble the battery and confirm that the 3 sets of batteries are all using the same type of protection board, and the batteries are all Sanyo batteries:
A. After testing the function of the protection board (overcharge, overdischarge, overcurrent protection, etc.), it is confirmed that its function is normal;
B. Detect the battery cells. The voltage of the cells in the middle of each group of batteries is lower than 1V.

Zhejiang Aolong Electrical Source Co., Ltd. was founded in 2004, located in scenic Shangyu Industrial Area of Shaoxing City, Zhejiang, China, occupied a land area of more than 70000 square meters, with more than 700 employees, the annual output of lead acid battery can reach to 10 million pcs. our progenitor company is Hangzhou Gold Dragon Battery Co., Ltd., which was founded in 1976 and owns the brand of GOLD DRAGON . Is a high-end professional company which with more than 40 years of professional manufacturing and management experiences, A collection of independent research and development, production, sales and service as one of the high-end professional lead-acid battery business enterprises, the main production and management products include motorcycle battery, e-bike battery, automotive battery, vrla sealed battery five series of hundreds of lead-acid batteries.