So its hardware issue i think ! i would suggest to talk to seller !
but as a last option you can install official ROM from here http://en.miui.com/download-101.html
and see if it solves the issue
Check this thread for hardware test on xiaomi devices. http://xiaomi.eu/community/threads/mi2-complete-hardware-test.19533/
perform the display its number 13
credit loaded . please check. Usually it does not take much time but as its manual credit load, so if its after mid night in china it might take few hour because i might be sleeping.
thanks