The right solution will be to get the LCD screen replaced due to the flickering, horizontal or vertical lines, it is clear that it has caused damaged to the screen the way it has been opened.
Such a replacement is easy, remove the screws , remove the bezels but be careful with it for not having damaged. Bring to the front gently for the cables are still connected. Here, you will be able to confirm whether there is any cable which has been disconnected or damaged.
In such a case, you will easily know whether there has been any cable issue resulting in the screen to act like this and if it is so, you will not have to get the monitor replaced. Pull the data plug out and replug it to see whether it works correctly. Check the inverter too.
As soon as you have replaced it, get back in inverse manner for getting it connected back.
The instructions are complicated if you are not used to it and the best way to get through it will be sending it to a Repair Shop.
Do not forget that an external monitor could be a solution too but do consider your means.