Unfortunately, the first thing that comes to mind since you've mentioned that the only thing you've really done was install WAD's is that you must have installed a different version of the system menu from the one you already had (or a system menu theme based on such a version) and that other version uses a different IOS from the one you already had but you didn't install the IOS for the new system menu so it can't run. (You can look at the list of WAD files to see if that's the case or post it and we'll see if we can interpret it for you)
Another option is that you installed a bad channel WAD and have a banner brick but I think it's still kinda hard to do anything with it without PriiLoader or a Boot2 bootmii
Anyway, the last test you can do if you have a gamecube controller is plug it into the 4th GC controller port, take it apart so that you can press all 4 directions on the d-pad at the same time and start the Wii while holding all of them. If it starts up in maintenance mode then at least it means your system menu's still intact (although, even then, I'm not sure what else you can do from that point on to actually fix anything. . . It might still be able to run retail games that way at least.)
Also, you might find this to be an interesting read but most of what it says requires PriiLoader or Boot2 BootMii.
https://sites.google...tesg/unbricking
EDIT : also, if what you say about no signal is no signal but it does have sound, that just means your TV isn't compatible with your PAL system menu (although your WiiMotes SHOULD connect if that's the case.)