It all started here: https://www.reddit.com/r/galaxynote4/comments/6c70pp/mmc_read_fail_fix/
hopefully my documented route and explorations and blunder with Note 4 repair can help those few Note 4 in the wild running into this increasingly common MMC fail issue.
I have two Note 4 phones and I used to own the Note 2. I always load a third-party heavy duty battery (think ZeroLemon 10k mAH). These battery have the tendency to make the phone quite heavy and I do drop them around quite a bit . To be honest I don’t think Saumsung make the most sturdy phones to be honest. My old Note2 died of an MMC_read failure just like my first Note 4. It is quite curious their symptoms are surprisingly similar in that your phone suddenly starts to restart by themselves and as its frequency increase eventually once you reset your phoneand one day you will suddenly be greeted with the dreaded MMC_read failure.
I tossed my first Note 2 as it was costing almost 200CAD or more to replace the motherboard. My first Note 4 ran into the same issue and I kept it around as a spare charger for the other ZeroLemons batteries I got. Spent another 300CAD getting my second phone by the time Note 7 are burning the world down. Lo and behold about less than a year afterwards the second one started random bootlooping as well. You just know that some components in their are getting loose… Damn Sumsung. My old iPhone 4 is STILL alive and kicking (after a home button replacement lol). In face, my iPhone Gen 1 is STILL alive and kick on the charging stand…. I wish any Android device can have replaceable batteries and with a nice stylus and external memories.. and that is all I ask for… not much, is it? I don’t care if it’s battery sucks as long as I can remove and replace it with something else… Unlike the shity shity internal ones nowadays we get all thanks to Apple’s trend.
Anyway back to the topic about how to fix your phone…. if you dare.
I tried the technique as outlined in https://www.reddit.com/r/galaxynote4/comments/6c70pp/mmc_read_fail_fix/ and actually manage to revive my first phone with almost great results. I did 165c over 7 minutes and definitely over cooked some components ( especially the cameras and focusing mechanisms as it is permanently melted partially along with some minor cosmetic damage), also I was an idiot by having the camera facing the upper heating element and also left a good S pen there… sigh. so many mistakes. I think the direction of the device facing up or down DO matters.
Now, I am doing heat reflow in hope of reducing boot loop issues in my 2nd Note 4. Today I subjected the 2nd Note 4 to 300F for 2mins in the oven (bottom element on only, putting it on some cardboard pad to avoid direct facing of optical element), and I will update here more as my gruelsome experiments continue.
I do have to say that my first Note 4 is alive and well and so far has not even had the chance to bootloop on me even once yet (but then again, I’m currently not using it as a primary phone so it is a bit biased. Will report later as I play with it so far… but HEY, at least it booted up where as before MMC fail nonstop.). I did get a MMC_read failure again while charging and downloading up (which caused it to heat up a bit and was partially remedied by cooling down and restart). So be aware, this is most likely not a permanent fix but if your devices is bricked and boot looping and will cost over 200$ CAD to repair as a three generations old device, what do you have to lose? Do it for SCIENCE!
Why I don’t switch to a new Note? I think you probably know the answer just judging by the information I provided above: those puny 3000mah batteries are a joke…. Note 4 was the only pen device with a removable battery… I would have switched if I could but nothing good came up yet.
Best of luck and I sincerely wish you the best. Note 4 is a great device… when it is not bootlooping and if you did not burn the focusing/camera lens, and if it is not MMC fail on you… and frankly, I am going to start baking all broken electronics like this for the next little while…until they are totally dead.
Note the damage flash units in the first trial…