I've been reading online that some people are receiving an error message similar to this:
ddi : mmc_read failed
ODIN MODE (HIGH SPEED)
PRODUCT NAME: SM-N910T
CURRENT BINARY: Samsung Official
SYSTEM STATUS: Official
REACTIVATION LOCK: OFF
KNOX WARRANTY VOID: 0x0
QUALCOMM SECUREBOOT: ENABLE (CSB)
AP SWREV: S1, T1, R1, A2, P1
SECURE DOWNLOAD : ENABLE
If so then there might be hope because I was able to successfully make my Note 4 go from a paper weight to a fully working phone. Aside from the error message in DOWNLOAD MODE there were multiple times where I had to remove the battery and place it back in because for some reason the phone wouldn't power on unless I did just that. I'm going to try my best to replicate what I did so that someone else can benefit from this.
You can find the files attached here in this link
***THESE FILES ARE ONLY FOR SM-N910T (SAMSUNG GALAXY NOTE 4 FOR T-MOBILE)***
***THESE ARE THE FILES YOU NEED***
1) ODIN 3.09
2) N910TTMB1COD6_Modem_CP.tar (5.0.1 Modem)
3) N910TUVU2EPE3_N910TTMB2EPE3_N910TUVU2EPE3_HOME_AP. tar (6.0.1 Firmware Stock)
4) N910TUVU2EPE3_CP.tar (6.0.1 Modem)
1)Place phone in DOWNLOAD MODE (volume down + home + power button)
2) Open ODIN 3.09
3) Place file N910TTMB1COD6_Modem_CP.tar in CP box
4) Place file N910TUVU2EPE3_N910TTMB2EPE3_N910TUVU2EPE3_HOME_AP. tar in AP box
5) Once ODIN is finished flashing the files power off your phone and go back into DOWNLOAD MODE
6) Place file N910TUVU2EPE3_CP.tar in CP box
7) Once the file is flashed your phone will be mmc error free and you will have a 100% working phone again.
If you're having any issues please let me know.
My phone was on the epk2 and it suddenly started freezing, took a little while to come on when it went to sleep, lags between apps. I eventually installed a app called "Wakelock" which did help and made the performance like almost new. But then if i would power - off my phone and tried to turn it back on, it won't come on unless i removed the battery and placed it back in. The phone wasn't charging when powered off, even charging leds wont turn on . Most times to get it to turn on when powered off, i just had to remove the battery and put it back in and it would turn on fine, and i started the "wakelock" app which made the phone run perfect as long as i never restarted it. Sometimes the phone while booting would go download mode, and gave the "ddi: mmc_read failed boot error" which lead me to this thread!
By time i began seeing these symptoms i really thought it a hard-ware issue and my phone was dying.
The first thing i did was tried wiping cache, didn't help. Then i tried doing a factory-reset, didn't help either.
Then searching on xda, i found a thread "Note 4 PIT Files For Repartiton" https://forum.xda-developers.com/not...-t-w8-t3282641
I followed the instructions, and flashed over the stock epk2 firmware together with this pit file ( from sam-mobile) https://www.sammobile.com/forum/showthread.php?t=30022for the s910t ( the one on the thread was not for 5.1.1 +)
After flashing both pit file and epk2 firmware, i booted into recovery and did a factory reset and then booted as normal.
Went through samsung setup, and the phone still was freezing abit. I still had the issue where i had to remove the battery to turn on the phone if powered off. But after doing this i saw that the phone started to be able to charge when powered off now.
In my hopes to fix the problem of the freezing and powering on issue, i decided to try NYiCoN's solution and followed his exact steps and flashed everything over the epk2. After it was done, the screen booted to "Optimizing apps" and eventually home screen. I then tried turning off and i can now power on the phone without removing battery, i haven't gotten the mmc read error and everything works like new.
This is what i did to solve my problem, i still can't believe it worked but i hope it can help others who have this problem and is thinking of replacing board. I now use my phone without the wakelock app as i don't need it anymore!