DeWALT Flexvolt 60V Battery Not Charging (How To Reset)

I own two pieces of DeWALT flexvolt battery.

Each of them is rated 20V/60V, which means it is flexible to either output 20V or 60V depend on the dewalt tool used.

One of my DeWALT flexvolt battery is not charging when I put it on the charger, the indicator light on my dewalt charger is dim when I tried to charge this faulty dewalt flexvolt battery.

When measuring using multimeter, a healthy dewalt flexvolt would output around 20V when measuring at the B+ and B- terminal.

For the unhealthy dewalt flexvolt battery, it only output around 3V, which is clearly something wrong.

To fix this issue, I tried to reset the dewalt flexvolt battery.

Connect the B+ terminal of the healthy flexvolt battery the B+ terminal of the another unhealthy flexvolt battery.

After that, use another wire to connect one end of flexvolt battery's B- terminal, and try to touch the B- terminal of another battery multiple times.

It would create some sparks which is normal.

After that, try to put the dewalt flexvolt battery back to charge again,