I leant my bike to a family member, and he put it out of use for the winter. Unbeknownst to me, he left the battery outside in -40°F weather all winter. I came to pick the bike up this following fall and the bike wouldn't start, showing no battery.... I charged it for over 24 hours and wonder if it's possible to fix the darned thing. The battery costs twice as much as the bike: should I dispose of it, try to fix it myself, or bring it to a repair shop?