Spreadtrum devices don't have recoveries, nor don't they have a ''download mode". Their bootloader is accessed with a "boot key" (usually hardware buttons) through **SCI USB2Serial** port.

To get the phone detected, just simply switch it off. Hold volume down button (or volume up) and plug the device to the computer. Windows should install drivers (Download and install [SCI drivers][1]). 

Open the flash tool (ResearchDownload), load the PAC file, click on run. Power off the device, hold volume up/ down, connect USB cable. Et voilà.


  [1]: https://forum.hovatek.com/thread-827.html