Most likely you burnt the Power Board, some units have a fuse but it takes a great deal to blow it and light spikes will still take out the unit while leaving the fuse intacted.
1. Check to see if they are still in warranty if so exchange them, I highly advise purchasing that extended warranty every store carries because it normally is 3 years over the 1-2 years manufacture warranty.
2. Out of warrenty what is the Model #'s, DIY repair is pretty easy I can set you on the path to the correct part replacement or let you know of any possible recalls.