New featherweight (DMBLBIT)

[Eventorizon]

Just to point out we drained one of Binky's 5S lipos down to around 2.2v-2.5v per cell in 2013. With the Big Nipper teams Pro-Cell charger it was recovered and has been functioning fine ever since.
The consensus used to be that dropping the voltage on a lipo used to be its death but now it seems with a few more years of testing that it is massive current draws that do permanent damage. It was hard to spot this as it usually took a high current discharge (expected or unexpected) to drop the cell voltage that low. (This info comes from one of the New Scientists magazines regarding electric vehicles that use Lipos while comparing them to lithium Ion)
Keep hold of it and wait until you are at an event where someone will let you use one of the top of the line chargers. It may be dead but I reckon it can be saved.