Hello there,
Everything i have read over the years say that an Li-ion cell that has a voltage
that falls below 2.5v should NOT be charged again due to problems that come up
inside the cell which could cause it to explode or start on fire.
Even so, if you do charge it and it doesnt blow up the capacity will probably still
be much less than it should be.
All this leads me to advise you to bring the cells back and tell the seller that he is
selling bad Li-ion cells! If he doesnt believe you or insists that they are good
anyway, im sure we can find many web sites that talk about this problem.
I once charged a cell that was around 2.4v before i knew about this problem,
and it did take a charge and didnt blow up but the capacity was wayyyy
lower than it should have been for that size cell, so it was not worth doing
in the first place. It's been thrown out since then.
A cell that shows zero volts has got to be really bad. Most cells that are shipped
these days have around 50 percent charge until they are recharged, which
means their terminal voltage would be above 3 volts at the least.