The first thing you need to do is open the battery case.🙂

Then check the voltage on all cells. If they are not equal to each other, then rebalance with some device (such as imax) or manually on each cell to a single voltage.

Then you need to disconnect the protection board and clean the contacts that connect it to the cells. I would advise then, when reattaching the board, either solder these contacts or weld them with spot welding.

After that comes the most important point. Most likely, you will have one LED on the indicator blinking the same way as before,...