Hi @lms7777
The reason I asked you to move the screen back and forth is that sometimes the video cable can get damaged where it passes through a hinge to get from the motherboard to the screen and by moving the screen you can make it happen or make it stop depending on exactly where the screen is situated.
Since it happens in any position it's looking like a screen problem or perhaps a loose video cable connection (either end) problem in the laptop.
To verify this, first connect an external monitor to the laptop and check if its display flickers as well.
If its display is OK then here's the [https://download.lenovo.com/consumer/mobiles_pub/ideapad_100_15_ibd_hmm_201508.pdf|hardware maintenance manual] for the laptop.
Go to p.58 to view the procedure to remove the LCD panel. This will allow you to inspect the video cable, check if the video cable connections at both ends, motherboard and screen, are secure and finally to replace the LCD panel.
Usually the Lenovo part number for the panel can be found on the back of the panel. For example it maybe something like this - 5D10H91342.
Whatever it is search online using the ''part number only'' to find suppliers that suit you best.
If the video cable is damaged then search online for ''Lenovo IdeaPad 100-15IBD-80QQ LCD video cable''