Hi @dragonsden ,
It may not be as simple as a fuse (if there is one) or the transformer. It may be something else such as a burnt out capacitor or diode etc.
Here is a link to the ifixit guide on how to remove the motherboard of the speaker.
Once you have accessed the motherboard you may be able to ascertain the extent of the problem. Hopefully it will be something that is obvious, such as a burnt out component. Again it is hoped that the information printed on the faulty component will be legible enough for you to be able to obtain the correct value replacement part.
If you have difficulty identifying an obviously faulty component, post some pictures and perhaps someone here will be able to help. Here's how Adding images to an existing question.
If there is nothing obvious to be seen you'll need to get technical and start doing some point to point testing of the circuit with the power disconnected, using an Ohmmeter, to narrow down where the fault lies.
Hopefully this is of some help