I've opened up and gutted a couple of MFB IR Control Beyblades from Hasbro before. They work a little differently to the Japanese ones, I believe.
In any case, you must launch the blade using the included launcher. Why? Because both the launcher and the blade have internal "reset" buttons which can only be triggered by loading the blade onto this particular launcher. The prongs and ripcord trigger the buttons. Triggering the buttons basically turns the blade and the launcher "on" and resets any current values in the computer (inside the launcher), ready for a new battle.
Okay, now the spinning mechanism:
The blade has a flat spin-tip attached to the shaft of a tiny electric motor. If I remember correctly, the motor itself is actually free-spinning. So the tip spins AND the motor itself spins in the housing inside the blade. The electircal connections for the motor are thus bearing-based and not soldered to the motor itself. Cool, no?
I believe the reason the motor itself is free-spinning (and not just the tip) is because there is otherwise a 100% torque-factor on the motor when you reverse its direction using the remote controls on the launcher. Having the motor free-spin dampens the acceleration and stops the spinning blade from losing control when you suddenly change the spin direction of the tip. Without this feature, the blade's actual spin would die almost immediately and I imagine the blade would literally flip out of the stadium.
There is also a shock-absorber at the rear of the motor so that the shaft does not grind when the blade drops onto the surface of the stadium.
Apart from that, the motor can indeed be used to "boost" the blade perpetually; except that the launcher has built-in software to disengage the motor once the blade runs out of "power" which is a super-annoying game-breaking bad idea from the designers and basically consigns the whole toy to the scrap-heap rather than the annals of robot-combat glory. But yeah, using that "boost" feature does indeed make the blade itself spin faster.
The PCB is nicely designed to be "round" and distributes its weight fairly well inside the plastic housing. The IR receiver is centrally located and the batteries are distributed evenly around the perimeter to increase spin times.
A cool mechanical design all up, with unfortunate game-design choices.