I am having a similar problem.
Brand new 4.2 Running SoftMod (As per the Forum) working fine with cIOS38 R14
I used WAD Manager to remove the NeoGamma R8 B7
Reebooted now no Video Output.
Not a black screen brick for I have one here that has the Black screen NAND brick and my TV detects the video signal on that one.
My wii has "NO VIDEO OR AUDIO OUTPUT"