Welcome to the Dell Community @SapphiraBeth
Did they replace the LCD panel???
You could also try a "Flex Test"
While the laptop is booted and the screen is on.
Grab the display at the upper left and right corners.
Then push one side forward and the other side backwards about 1/2" to 1"
Repeat back and forth. "Flex Test"
Post any changes in the display.
I just tried it but nothing happened. I have a gut feeling that it's the display cable, but I don't know how to find out. That and I really don't want to spend $200 something to replace the motherboard
85% of the time it is the LCD panel.
10% of the time it is the LCD cable.
5% of the time "or less" it is the system.
Does it flash off then back on???
If it does "Flash Off" is there a faint image in the background but no brightness??
Does it flash with "Lines or Columns"???
The LCD panel !!!
With those symptoms the first thing my tech's would do is replace the LCD panel!!
It would fix the problem 99% of the time.
We replace 50+ LCD's every month with the same symptoms.
But I used the inbuilt test while booting up the system to check for it nothing showed up, that and the technician i went to checked the LCD panel he said it wasn't working.
oh and i failed to add the fact that I tried to open up the laptop, but i didn't really touch anything, and it went as well as i'd have expected it to, and i don't know if that could be one of the problems