I had multiple things associated with the ZIF connector, the blinking screen bit is more in line with the lockout chip failing to communicate between cart and board over the connector. scrambled graphics depends on connection of the other pins involved in the series of pins. Did you ever use something like a Game Genie with your NES? These due to their nature of the design, were pretty stiff and caused damage to the ZIF connector and basically made it so that you had to use it to start your games Even if you didn't want to use it. Best advice, if it's been sitting in storage for a long period of time, it's a good idea to open it up and clean it up from the inside anyway, at least you can get a good look at the connector pins that way,(check for dirt or corosion) as well as check the condition of the caps of the board. (another failure point of these older systems) And while you are in there, do the lock out chip pin snip to stop blinking screen.

I had multiple things associated with the ZIF connector, the blinking screen bit is more in line with the lockout chip failing to communicate between cart and board over the connector. scrambled graphics depends on connection of the other pins involved in the series of pins.

Did you ever use something like a Game Genie with your NES? These due to their nature of the design, were pretty stiff and caused damage to the ZIF connector and basically made it so that you had to use it to start your games Even if you didn't want to use it.

Best advice, if it's been sitting in storage for a long period of time, it's a good idea to open it up and clean it up from the inside anyway, at least you can get a good look at the connector pins that way as well as check the condition of the caps of the board. (another failure point of these older systems) And while you are in there, do the lock out chip pin snip to stop blinking screen.