NC does not qualify, nor would any car should it have a salvage title _OR_ (in states where such a title does not "exist) has been previously "totaled" whether restored or not. True for all manufacturers not just Honda and applies to all warranties. Caveat emptor.
For the rest of the story in regard to battery costs and updated controllers see my post here:
Find a pack from a wrecked Insight and select the best cell subasemblies from the pair of them. It has been done by at least one of the members here. Usulally it is just a small percentage of the cells that are weak. Quite possibly you can find a salvaged one that doesn't need rebuilding.
There is a thread in Mod & Tech on the topic of self rebuilding. (Calpod's :?: )
But he wasn't sucessful. His commercially available battery loading / charging device did not load at a high enough rate to accurately evaluate a sub packs condition.
Its not an exactly an issue of safety. But if your IMA pack won't provide much assist then about 20% of low end power is not available. The biggest problem is that the 12v charging system is integrated with the IMA system. Once the 12v battery light comes on your in 12v discharge and like in a conventional car you'll be walking very shortly. And before you ask there is no off-the-shelf substute.
You can try the IMA reset proceedure. Simply disconnect the 12v for about 1 min, then expect a forced charge. If the 144v battery is bad expect a return to your current condition within a few days. If its really bad then the resulting forced charge will likely not be able to "refill" the IMA pack.
Now you've got to decide new vs. used and DIY (or with someones help ). And whether or not you want to go for the updated IMA controllers too.
Search eBay for current pricing, but with a bad IMA pack I'd expect you'd have to take that cost right off the top.
If the RED IMA light does not stay on (or come on when driving) then its not related to the IMA system (directly anyways, but I digress).
You've got an engine fuel or emissions problem of some type. You need the code pulled.
And its probably too soon to rest easy in regard to your eariler IMA problem. Remember SoC is NOT a reliable indicator of the remaining service life of the 144v battery.
Batteries commonly fail by degree. You _may_ expeirence the IMA light repeatedly weeks - months apart, with an increasing frequency (each particular code will be beneficial in diagnosis rather than simply clearing it without a record). Ultimately you will get them daily or continously. Its then that the 144V battery won't "wait" much longer.