It won't bootup to with the sprint logo until it is activated. If they flashed it to another carrier then that was removed. When you open up a brand new phone on first boot you won't get the Sprint logo until the phone fully boots and activates then it installs the Sprint specific files. What you should do is download the full mf9 tar file and install it with odin to make sure the phone has the correct radio and modem files installed for sprint network, then do the ##72786# entry in the dialer to factory reset the phone and activation status. Then try to activate the phone with Sprint.
Phones & Tablets: Galaxy S4, Galaxy Note 8", Evo 4g LTE, Evo 3D, Acer Iconia A500, Samsung Galaxy Tab 2 10.1, Ipad 2, Nabi 2,
Rom: Rooted Stock for now, Hotspot Mod, Xposed, Wanum
Kernel: Stock for now