My nexus 7 2nd gen hasen't been on in a couple months due to a screen crack and i was just wondering if the battery would be damaged if i were to get it fixed and if it would be a waste?
The battery is probably pretty dead now. I'd charge it for about 6 hours before sending it out to be fixed. Then I'd condition it when I got it back (The Care and Feeding of Lithium Polymer Batteries). My V551 batteries are over 10 years old and sat on a shelf for about a year, one in the phone. They're still almost as good as when they were new.
If you've regularly been discharging the battery down to 10% or so, though, it's probably at end of life, so I'd ask whoever is repairing it to put a new battery in it while they have it open. (Then condition it when you get it back.)
"Conditioning" a modern lithium ion battery is an old wives tale, and there is no reason to do so, nor to worry about how low it gets before charging, which has absolutely no effect on total battery lifetime.