maybe the battery is dead. IIRC, it will not turn on with a flat battery.
If you bought one of those cheap ipod 1/2 gen batteries that need the wires swapped, it may be the battery is broken. I've had it with my h340... Those ipod replacement batteries are crap.
Open it up and check if the battery is inflated or leaking. If you still have the old battery, try that one again