How to enable AWS band on Galaxy s4 SGH-I337M? Phone stats:

Make:                  Samsung Galaxy s4
Model #:               SGH-I337M
Android Version:       5.0.1
Baseband Version:      I337MVLUGOH1
Kernel Verion:         3.4.0-4508315
                       DPI@SWHD7402 #1

Old Carrier:          Telus  (unlocked by carrier)
New carrier:          Wind mobile

Problem:

After researching web/youtube, I had bought the S4 on the premise that I could add the AWS band on to the phone with relative ease after watching a youtube video tutorial. (I'm not extremely technical but I'm a DIY guy and thought I could take on the challenge) 

After purchasing the phone, I started following the steps in the video and quickly realized that the OS on the tutorial was older than my newly purchased phone with a updated OS. First video I found, told me to use a code *#7284# to enter into the modem settings (which no longer works for some reason). Then I found a video that asked me to enter *#0808# (this does work to get into the settings the tutorial asked me to change). The problem is, that after I change the settings from "MTP" to “RNDIS + DM + MODEM”, my phone will not connect to my computer and thus renders me unable to continue with the tutorial. (computer says "unable to identify USB connection")

I'm worried because I need to have my phone up and running before the end of this month because I have to return a shitty ACER phone I purchased temporarily from costco is running out of its 90 day return policy. 

I know the phone is already 2 generations behind its predecessors but I'm hoping someone in this forum can help me out! 

I've been following these steps: http://forum.xda-developers.com/showthread.php?t=2291589

Thank you in advance,

Matt
In addition to changing from *#7284# to *#0808#, I also had to temporarily go back to the stock recovery from TWRP so that I can "enable cp logging".  If I don't do that, QPST (the program you have to run to add AWS) simply cannot find the connection to my phone.   

Originally I was afraid that going back to the stock recovery would remove my root, and I would have to re-root again before I can install TWRP.  It turns out a non-issue.  

Just a reminder when your attention is so warped up with this AWS challenge,  Odin cannot flash a recovery.img file (which you extract from the stock ROM).  I should have known better.  After some frustrating moment, I archived this file into the .tar format and Odin flashed it without a glitch.