Well I think that you have to go inside of the orange doors so that you cancomplete the level and move on to the next level then. Or there was a mistake while it was being made.
Well i have heard of this before it either might mean that the gampacks are dirty and need to be cleaned or and the pinconnecter is messed up and needs replacing. Qutips and rubbing alcohal.
Well it depends if there is another issue with the console if it works okay and the light bulb burns out it will be fine if it bugs you alot why don't you send it into repair somewhere then and they will fix that problem for you.
Well I think that the lockout chip might be causing the issue and there are web sites that show and tell you on how to do lockout chip removal for NES.
it could be your TV, if your tv has video adjustment, just mess around with the options until the picture comes in clear, if that dosn't work, than it's probably the RF box on the motherboard (if you wanna know what that is search it up, but it's very technical), try getting a famiclone, new third-party NES's, i recommend the Retro Entertainment System, it works great and cheap on some sites. If that dosn't work, try a diffrent TV.
First i would try to hit the reset button while the screen flashes especialy if the title screen is flashin if that doesnt work watch this video.It helped me fix my NES!!