I had originally filed my taxes using Sprintax but I need to amend the tax returns uisng Turbotax? is that possible? if Yes, please let me know how

yes it's possible. you would need to reenter everything using the Turbotax desktop version as if you were filing the original return. then save the return. then reopen it and click on the amend icon. you need to check every line to make they match the Sprintax return. you will have to mail it.   expect a refund to take 6 months or more. 

you are better off using Sprintax to amend. 

The TT program doesn't handle the form 1040-NR at all ... only sprintax handles that form so if you need to amend the return go back to sprintax.