Hello my name is ***** ***** I will do whatever I possibly can to help answer your questions. I am sorry you have encountered this kind of problem. It sounds like you may have a loose connection to screen. It's possible the video cable may have came loose. Or The screen damaged. When you move the lid open and shut does the screen react at all?
Sadly the only other way would be to disassemble the lcd assembly to disconnect and reconnect the video cable of course if that fails to fix the problem you would be looking at a replacement screen. When you move the lid does the screen flicker at all when it's at the lock screen?
It's not at full resolution when its at that screen until it boots as well. ok can you shut the machine down, remove the battery run only on external power and tell me if it does the same thing.
That is correct
I am concerned this is a led screen problem, Since I don't have the model number of your machine at this time. Also given the characteristics it seems when it goes to a higher resolution is when it starts to do this. You may be looking at a replacement screen. It's either that or your graphics card was damaged during impact it would have to be one or the other. This is sadly a hardware malfunction. I would highly advise taking it in to have it checked out.
If it's a laptop the graphics card is built into the motherboard usually the entire board gets replaced. You can usually find a replacement on ebay. You would need to include the model number and type motherboard or screen or led screen to locate a suitable replacement but if you don't know how to take one of these machines apart a local computer repair store would be able to tell in person which part would be causing the malfunction.
Your welcome I am just sorry this happened to you. Let me know if you have any further questions.