I'm dizzy from looking at so many laptops I finally decided on precision m7510 I got all the specs I was looking for (i7 3.7 4 core 8 thread, 512 pcie nvme class 40,ect) in confusion of looking at so many ads trying to get best deal (I'm CS student) I wasn't paying attention and the m7510 I ordered didn't have backlit keyboard I wanted can I change non backlit keyboard to backlit keyboard on m7510???
I normally do not handle questions on Precision systems but thought I would try to help. Anyway, I know on the previous models you could upgrade to a backlit keyboard on both the Latitude/Precision lines, so you shouldn't have an issue on the m7510. The part number you're looking for should be 383D7 and you can enter your Service Tag here to see if the part is available or call 1-800-357-3355 for the Dell Spare Parts department (if you're in the US). I would recommend calling them or at least confirming what connections you see on the motherboard before ordering (for the backlit keyboard to work you should see a spot on the motherboard for an extra ribbon cable to be plugged in), and also make sure that you're comfortable with the install (here is a direct link to the steps).
Please note that as per Terry's post here that this is not something that would be covered under warranty if something went wrong, but again, if you're comfortable it should not be too bad.
Another option if you're within the return period is to re-order and return the system, or see about exchanging the system for one with a backlit keyboard.
I hope this helps. And sorry to hear the order didn't go as planned, I have done something similar on a new build myself