Dell Latitude E5470 screen is very dim(backlight not working)

Question

My Dell Latitude E5470's monitor stopped working a few days ago. I connected an external monitor and it was working fine and then I realized I could kind of see the Dell logo on start up when there is some light shining on the screen. I tried the battery drain, unplugging the battery, taking out and putting back the RAM, and unplugging and plugging in the EDP wire and nothing worked. I have also ran diagnostics from Dell, updated all the drivers, and run the built in display test and nothing affected it.

I took out the monitor and plugged in the EDP wire on my friend's laptop(the same laptop model) and it worked fine, and I plugged in the other laptop's monitor into mine and it was still dim. I went into BIOS, and by constantly moving the light and trying to read the options, I raised the screen brightness settings and still nothing changed.

Common solution I have been reading is checking the inverter and I don't think this laptop has one and even if it did, why would it work on another laptop.

Please let me know of any solutions you can think of. I spoke to dell and as my warranty has been expired they will charge $50 just to check it out and more charges if they have to fix it, and I would rather see what I can do before going forward with that. Thank you.