1. The power of the charging bank is insufficient.
2. The charging bank has been damaged, you can try to use the charging bank to charge other mobile phones to check whether it is damaged.
3. The data cable connecting the charging bank and the mobile phone has been damaged, you can try to change the data cable or insert the data cable into the computer to check whether it can be charged.
4. If the phone cannot be charged for its own reasons, you can try to change the charging bank.