Want to upgrade your own RAM? Then you'll have to go with the older Latitude 7400. The newer Latitude 7410 adds a few new features while taking away some others at the same time.
https://www.notebookcheck.net/Dell-Latitude-7410-vs-Latitude-7400-Is-Newer-Really-Better.480395.0.html
I guess the point that 7390 & 7400 have a manufacturing flaw which has been finally rectified in 7410 is missed out. If you have a doubt, lift the laptop with you left hand by holding behind the numeric 1 key !! 8)