I would start by making sure you replaced the battery in the chip correctly and that the chip is reconnected flush to the chip holder on the cartridge. The batter should be flat side UP with the chip laying flat on the surface or it won’t read. Here is an article with pictures for battery replacement in these chips http://www.inkjetmall.com/tech/content.php?169-Battery-Replacement-for-4900-and-R3000-Chips I would recommend you replace ALL the batteries in your cartridges so you don’t have to go through this again, this will save you the nightmare you are encountering right now.
Chances are the LLK cartridge had a dead battery OR a faulty chip and it is causing recognition errors on the Cyan cartridge. Start over from the beginning and check the battery in the LLK chip, if it’s installed correctly then you may have a faulty chip. If you correct it and you get a reading, make sure you start out with the same exact scenario you did before this mess, reinstall the Epson C and which ever VM cartridge you had installed (making sure to replace the battery IF your using our refill cart).
Let me know what you find, I hope it’s just a battery installed upside down, if not we will get you a replacement chip in the mail asap.