The integrated GPU on 2400 performs as good as a GT 1030. I'd say wait for a few days for the GPU prices to get stable.
You can invest more in RAM for better performance!
There are no chips/dings on edges or corners. Box and original charger is not available but a 2A charger will be provided!
There are no scratches on the screen; the crack (not so visible) is present on the screen guard!
This is a 16 GB version and the tab is running stock android (rooted).
I'd say keep JioFi2. Although it has a smaller battery, build is much better. People have reported a lot of issues with JioFi3 (even for me, WPS button doesn't work anymore).
I don't think you'll get to know the name, not easily at least (they might've extorted money from him for it)! And yeah, if you want to continue with it you'll need a lawyer!
It is probably due to faulty memory. Try booting without RAM, if motherboard is fine it should give you three long beeps. If so, try putting the RAM module in different slots. And if you could manage a RAM stick, that'd really help in determining where the problem lies (and also, solution...