What f(x)tec euphemistically refer to as a "sleep state" means nothing else than that the battery erroneously got depleted to literally 0.0 V, so that there is no energy whatsoever left in it. The "battery protection" system should normally prevent this from happening. Not only is so deep discharging bad for a Li-battery's life expectancy, it also turns out that Android actually always needs enough residual charge left to boot its kernel before re-charging from USB can start.
So, yes, once bitten by the battery depletion bug, there is no other way than to either 1) send the phone back