There is a procedure for charging eGo batteries for the first time:
1. Place the battery into the charging cord and plug the cord into the USB converter (the part that plugs into electrical outlet), and then plug the converter into the wall outlet.
2. Charge battery for a full 8 hours, even if the light of the charger turns green.
3. After an 8 hour charge, unplug the charger and remove the battery.
4. Now use the battery for 20 minutes,
vaping normally.
5. Place the battery back into the charger and plug the charger into wall outlet for one hour, even if the charger light turns green.
6. Now your battery is ready for normal usage.
Please note that after the initial charging procedure described above, you never have to do it again with the batteries after the initial charge procedures. From now on, when your battery indicates that it needs to be charged by blinking briefly, plug the battery into the charger, plug the charger into your wall outlet, and when the light nearest the battery turns green, you're finished! Some suppliers also advise making each charging session a minimum of three hours long, but I've not seen any performance difference with my batteries if I only wait until the green light. However, YMMV.
These instructions should have been in your shipment. You can always check the internet for first time charging instructions of just about every battery type. These procedures will ensure that your batteries will hold a full charge and accept a greater number of charge/use cycles in the future.
Now about your battery that is not behaving as you expected: If your battery's led button blinks briefly when you plug the charger into the wall outlet, then the battery is low on charge and that's normal, so just try the procedures for the first battery charge. If your battery's led button blinks around 20 times when you press the button, then your battery has probably malfunctioned and is no longer safe to use.
If anyone else knows of some better advice than I, then please share it with all of us! Happy Vaping, xenoriz!