Xiaomi Mi4 Miui V5 Upgrade Problems

Feb 3, 2015
I recently puchased a Xiaomi Mi4 and I am trying to upgrade the version of Miui but having problems.
I would like to upgrade to Miui v7 or Miui v7.1

Model Number: MI4W
Android Version: 4.4.2 KVT49L
MIUI Version: Miui v5 KXDCNBF21.0 (Stable Build)
CPU: Quad-Core 2.5Ghz
RAM: 3.00GB
Kernal: 3.4.0-g26e4aff-0900-ga93b357
Root Permission is "off" and greyed out so I cannot change it.
I cannot access "Manage Root Permissions"

1. Clicking system update doesn't work.
2. Moving update.zip to root and rebooting phone doesn't work.
3. Moving update.zip to download_rom and rebooting the phone doesn't work.

I would be grateful for any help and advice.