I don't think 20 second holds and taking the battery out will do anything to affect booting.
Holding the power button for 5 seconds signals the circuitry to generate a reset, and it is fully as good as taking the battery out for booting problems. Certain hardware subsystems (network, etc) may behave differently on cold boot but it won't change the fact that it won't boot at all.
The critical thing that I haven't heard is whether it has power. Does the power light come on when it's plugged in? What does the battery charge light indicate? I would plug it in, let it sit for a few seconds, observe the lights, and then hold the power button for 5 seconds.