2008 prius battery replacement questions

i have a few questions. I have a 2008 prius with 110k miles.
I bought it 5 months ago from a person who rebuilds batteries.
now i have red triangle.
ODB2 say bad battery , probably cell 10.
I am thinking of replacing module 10 myself since i am usually good at hands on stuff.
1. can i do this with just my basic hand tools and a voltmeter?
2. if i dont balance the batteries will they balance themselves if they are all together for a day or so?
3. do they need to all be at the same volt. like if the new one is at say 8 , and the others are at 7.5 ?
- thank you for your time