LG P500 Not Starting After Full Discharge My LG P500, with FroYo, doesn't seem to be working. I let my battery completely die and now, even while plugged in, it won't turn on. Is this normal and should I just wait the battery to be charged out of the critical zone? Or is there something wrong?
As Avio's answer says this is normal, but I assume you're wondering why.  It's because the battery doesn't have enough charge to keep the voltage level up.  The hardware will only work within a certain voltage range, just like PC hardware for example.  Most (all?) phones don't have the redundant circuitry and so on to allow them to be powered directly from the USB port while the battery charges, so you have to wait till the battery charges to the minmum required level.

As an aside, Android normally shuts down with about 5% of battery left, avoiding this problem.  Unless you turned it back on after this point, it might be that your version doesn't do this or that the battery stats are messed up and need to be wiped.