are you sure the t.v. is set on the right input channel? the only problem ive ever had with 64 is the power box burning out... clean the games with alcohol, or game cleaner "same thing" never anything water based you will ruin the pins on the cartridge... might help it work the first time but will slowly kill the game and system..you might just have a bad set of AV cables too if they get bent to far one way they wont work after that i had 5 inputs on my t.v. before i got a switch box 4 on back one on the side.. the side pinched the wire so tight in the entertainment system it killed the cables... had to get a new set... if you know anyone with another 64 or GC even they use the same av cables... try a new set if cleaning the game doesnt work.
Yea man, I used to get this problem occasionally with my old 64. The power would come on but no picture. A few switches on and off with the on/off switch and pulling the battery pack out and putting it back in always did the trick. This seems to be as common as the NES and having to toy with it to get certain games to come up without all the glitches. Good luck, but this shouldn't worry you... and my advice: don't spend any money on it.