Originally Posted by rhodesengr
you can also try to cycle them. If you charger has a discharge mode, run them down and recharge a few times. If they get too low where you get a low voltage error on your charger, you can charge them as an NiMH to get the voltage up.
If you cycle them, and they still don't power your model, then you can declare them shot.
Cycling doesn't revitalize dead Lipo, and charging as a NiCad/Nimh will produce the magic smoke real quick
As Petefoss noted, Lipo which have been stored fully charged degrade chemically and seems to have very low capacity because of higher internal resistance.