several aircraft were damaged by SA using incorrect GPU's on the aircraft, which did damage, as the wrong GPU's didn't have current limiters, so fried bits that were not capable of taking the current drawn.
Apart from the fact that the above is technically incorrect ("bits" don't take any more current than they need, unless they are shorted out), it illustrates the problem. Most aircraft have limiting devices at the point the power enters the aircraft, and that prevents damage to anything capable of being damaged by excess voltage or incorrect frequency. The components necessary are not that big or expensive. Omitting them just gives some idea of how cheaply some aircraft are built - I don't know if the Q400 has them or not, but I suspect "not".