Hybrid battery repair

Hi everyone, I'm a new guy here. I've been researching how to repair my battery and have seen many contradicting answers so I hope I can get some answers here. I am no electrician so I need step by step if possible. I'm replacing one of the modules in my hybrid battery. All modules read 7.78 volts except for the bad one.

Here's my question, when I get the new one in, what EXACTLY do I need to do? I've seen that you have to balance it with the other ones but I have no idea how to do that. I'm not too electrically inclined so I need it broken down to like 1st grade level haha.

Also, if the new one reads 7.7 volts, do I even need to do anything? Thank you in advance