I’ll try to help. You’re right about the colour coding. The plain copper will be the common, going to both earpieces, with the green and red going to right and left respectively. Probably. I don’t think there is a colour code standard for ‘phones. Anyway, you need to reconnect the tiny tiny wires. The conductors are very thin as you have noticed and they are twisted/bound with fibre. This is to maintain flexibility and prevent the conductors from breaking when repeatedly twisted/flexed. They are not meant to be soldered, but I have done it - you need to remove all the fibre to leave the copper then carefully scrape off the laquer to reveal the bare metaL. as you have discovered, any heat on the fibre from the soldering iron will cause burning and this will get on the copper wires you carefully exposed. You need a steady hand, close-up specs (if you wear them) and soldering flux. You have to do it quickly, everything must be super clean and held ready in position. Alligator clips can help with positioning...