I like porn and my head hurts!
Person asking all these questions, are you keeping these batteries as "matched sets", or "married"? You need to have batteries that are charged and discharged as a pair, or trio, whatever the case may be for your mod. If you are not, you are going to have continuous problems of this nature! If not much worse!
I'm honestly not sure that's now what happened here, are all the batteries the same? Somehow I doubt it.
As for a 3600mah 18650, someone lied to you! The battery that went was a re-wrapped low rate battery, sold to you as a way over ratted battery.
In the future, stick with Sony, LG or Panasonic, buy them from RTDvapor, Illumination supply or Orbitronics. YES, you will pay a bit more, but you will get a GOOD, SAFE battery!
Take the batteries you have, dispose of them properly, buy two sets, if it takes two batteries, buy four, if it takes three batteries, buy six. Buy a GOOD charger, from one of the vendors listed above, LABEL the batteries in a manner you will understand that they need to STAY together. Then charge them together, discharge them together, then charge them together and so on! But keep them as they are married and can't be used alone! Please!