[Nexus 4 Q&A, Help & Troubleshooting] vikas_toad:
Now i know this thread is a little repetitive but this thread covers the red led problem in detail and also covers various scenarios of red led.

I very recently had a red led situation and had to scourge through various threads to find a solution and every thread covers a different solution.

I Have merely scourged, understood compiled and explained in detail all the problems related to nexus 4 Dying out and their solution. All the credits go to every person who originally provided these solutions in their threads (a lot many :P)

RED LED: All 4 SCENARIOS - All 4 FIXES

:DJust Follow the steps and you will be up and running with your phone in no time:D

Description: What happened was, you were merrily spending some beautiful moments with your phone but suddenly, the phone died and the red led started blinking and you felt like your world came crashing down. Then you attempt to restart you phone but nothing happens and the red led blinks again...even stops blinking after sometime, and now you feel that the time of your nexus 4 has come.But fret not... read on.. and you will be reunited with you living and fire breathing nexus 4:laugh:​

SCENARIO 1:RED LED (OR NO LED)- LOW CHARGE

What actually happened:

The battery drained completely (below a threshold level).This is different than normal discharge to empty and any attempt to reboot the phone results in the red led blinking or nothing at all indicating the battery is extremely drained.​

Why it happened:

Its a fault from LG. The Battery Calibration circuitry or logic is a little messed up allowing the battery to discharge below a threshold and then stopping the discharging rather than stopping it before.​

Solution:

Well this is the most non-worrying scenario to come out of. You simply pop-in the wall charger to the phone to allow it to charge. Initially red led will blink and after some time the charging indicator comes up on the screen. It may also happen that once you connect the charger, red led will not blink. Don't worry keep the charger connected. Ultimately the red led will blink and then charging indicator comes up(red led blinking may be skipped). Let it charge for a minimum of 20 minutes allowing the battery to charge about 15% before attempting to turn on your phone, other wise the phone may be stuck on the google logo while starting up.then charge the battery to full capacity and you are good to go.​

SCENARIO 2:RED LED (OR NO LED)- BATTERY CUTOFF

What actually happened:

Again the battery drained below a threshold OR due to the messed up battery callibration and the phone circuitry cuts off the battery even when the battery has some charge left.​

Why it happened::

Fault at LG's side. Bad battery calibration implementation.​

Solution:

A Slightly Difficult but only solution is to disconnect the battery. You do this by opening up the back and only disconnecting the battery connector for about 1 minute..this resets the battery cut-off then connect it again..put on the back.. charge for minimum 20 minutes.. the battery charging indication should come up on the screen, let the battery charge fully and you are good to go. Search on google for nexus 4 disassembly videos to know how to disassemble the nexus 4.You just need to open the back(the most detailed disassembly video is from "LE55ONS" on youtube). Be cautious while opening the back by not applying too much force or pressure.​

SCENARIO 3:RED LED(OR NO LED) - BATTERY DISCHARGE AND CUTOFF

What actually happened:

Again the battery drained below a threshold AND due to the messed up battery calibration and the phone circuitry ALSO cuts off the battery.This Scenario is a combination of of Scenario 1 and Scenario 2.​

Why it happened::

Again the blame goes to LG's Bad battery calibration implementation.

Solution: A little more complex than the previous solution.You have to open the back and charge the battery externally. Just open the back, disconnect the battery connector. Now rip apart a micro usb cable and connect(use tape) the red wire to the +ve terminal and black wire to the -ve terminal.

​

then

charge the battery with the original wall charger for not more than 10 minutes!

.

then connect the battery back to the phone and now charge the battery via phone to the full capacity. and you are done​

NOTE!

Remember! since you are charging the battery externally, there is no charging circuitry involved to stop the charging when the battery is full.and you just need the amount of power required to boot up the phone. charging the battery externally for 10 minutes should charge the battery about 5-8% which is very much enough to boot up the phone.

I WOULD SUGGEST FOLLOWING THE ALTERNATE METHOD BELOW

Alternatively, if you are a little paranoid over electricals like me, you can trickle charge the battery, means, instead of using the original wall charger that outputs 5v @ 1A, you can use old mobile chargers that usually output 5v @ 100mA. upto 250mA is fine. this way you can and have to externally charge the battery longer(without causing damage to battery) to regain 5-8%.

This solution was originally provided by http://xdaforums.com/showthread.php?t=2250454&highlight=red+led Big thanks!​

SCENARIO 3:NO RED LED, CANNOT CHARGE, AND YOU HAVE TRIED ALL THE ABOVE SOLUTION

What actually happened:: Faulty unit

Why it happened: Manufacturing defect.

Solution: Unfortunately, you will have to RMA your device :(

***************That was all the causes of the red led and their solution.. hit Thanks if this helped or you found it helpful :)*******************

Cheers :D and wish you a happy life ahead with your beloved Nexus 4 :fingers-crossed: