Hello and Welcome to this Guide!!!
As anyone know so far, the LG G3 is anything but reliable, mostly because it's constant tendency of overheating.
==================================================
The Main Reason:
-Poor Manufacturing (Remember the LG Bootloop Fiasco with the G4/V10/V20/Nexus 5X??
)
-The Huge Square Gap between the SoC and the Frame (Who the h*** designed this phone anyway?
)
==================================================
The Consecuences:
-Screen Dying or Flickering
-Rebooting,
-+60° Overheating
-Wi-Fi Loss (Not turning on or MAC displaying zeros)
-SIM Loss (IMEI displaying zeros or not displaying at all, or SIM not recognized)
-G4/G5/V20/Nexus 5-Style Bootloop
-Infrared Remote not flashing
-Etc.
==================================================
So I made a simple (or more reliable) solution: Aluminum Foil Heatsink
Since this is a Hardware Issue, I research over the time about homemade "solutions" like:
-"Card on SoC" and
-"Paper Below Rear Camera"
-(And my favorite)"Put a Thermal Pad between the SoC/RAM and the Frame"
Useless and Ridiculous Solutions if you ask me...
Reason 1: To dissipate heat you need and energy conductor, not an insulator!!!!
Reason 2: Thermal Pads are garbage, They insulate more than it can conduct heat.
==================================================
Now, before anyone has any complaints regarding using a little of Alluminum Foil inside the phone, let me clarify some comments about it:
-The phone frame is metal too (Surprising Right?? :silly
-The antennas are on the opposite side of the SoC, and on the bottom of the phone, so this WON'T interfere with network signal.
-Alluminum (as well as the other metals on the Frame and PCB) can ground, but since we are using the Stock EMI Shield, this fix cannot touch anything inside the EMI Shield. So there is NO RISK in doing this.
==================================================
We going to need:
Thermal Grease (I recommend Arctic MX-2 for this fix and to do Computer Maintenance)
Allumium Foil (You sould have a roll on the kitchen right??? Basic stuff to have at home right????...)
Screwdriver (Seriously, Do I need to explain myself???)
LG Electronics G3 D85x (Obviously) [My device is an T-Mobile variant: D851]
First, The Main Problem (At lease in my case); The Screen Dying:

YouTube or IFixIt has the dissassembly tutorial, to avoid wasting time part by part, i just put the back plate off

Here's what we got:

Here's what we need:

You have to bend it until you have a litte square that can fits the SoC space but can have a little height



All right; Like the third photo: You have to put thermal grease on both SoC and Display Chassis, and put the square on the chassis or the SoC (better on chassis when assembling)...
View attachment 4053916
Carefully you reassembly the Motherboard starting with the upper zone, reconnect and DONE!!!!!
Results:
Before (With Thermal Grease):


After:


Information:

(Remember, This may o may not fix the problem at all; It can be temporal or not, depending the dissoldering status of the SoC/RAM)
(May 2023 Update: I replaced this phone for a PH-1, then a Xiaomi Mi 9, and now I have a Samsung Galaxy S20+; the G3 was dying anyways, so glad LG stop making unreliable POS devices)
As anyone know so far, the LG G3 is anything but reliable, mostly because it's constant tendency of overheating.
==================================================
The Main Reason:
-Poor Manufacturing (Remember the LG Bootloop Fiasco with the G4/V10/V20/Nexus 5X??
-The Huge Square Gap between the SoC and the Frame (Who the h*** designed this phone anyway?
==================================================
The Consecuences:
-Screen Dying or Flickering
-Rebooting,
-+60° Overheating
-Wi-Fi Loss (Not turning on or MAC displaying zeros)
-SIM Loss (IMEI displaying zeros or not displaying at all, or SIM not recognized)
-G4/G5/V20/Nexus 5-Style Bootloop
-Infrared Remote not flashing
-Etc.
==================================================
So I made a simple (or more reliable) solution: Aluminum Foil Heatsink
Since this is a Hardware Issue, I research over the time about homemade "solutions" like:
-"Card on SoC" and
-"Paper Below Rear Camera"
-(And my favorite)"Put a Thermal Pad between the SoC/RAM and the Frame"
Useless and Ridiculous Solutions if you ask me...
Reason 1: To dissipate heat you need and energy conductor, not an insulator!!!!
Reason 2: Thermal Pads are garbage, They insulate more than it can conduct heat.
==================================================
Now, before anyone has any complaints regarding using a little of Alluminum Foil inside the phone, let me clarify some comments about it:
-The phone frame is metal too (Surprising Right?? :silly
-The antennas are on the opposite side of the SoC, and on the bottom of the phone, so this WON'T interfere with network signal.
-Alluminum (as well as the other metals on the Frame and PCB) can ground, but since we are using the Stock EMI Shield, this fix cannot touch anything inside the EMI Shield. So there is NO RISK in doing this.
==================================================
We going to need:
Thermal Grease (I recommend Arctic MX-2 for this fix and to do Computer Maintenance)
Allumium Foil (You sould have a roll on the kitchen right??? Basic stuff to have at home right????...)
Screwdriver (Seriously, Do I need to explain myself???)
LG Electronics G3 D85x (Obviously) [My device is an T-Mobile variant: D851]
First, The Main Problem (At lease in my case); The Screen Dying:

YouTube or IFixIt has the dissassembly tutorial, to avoid wasting time part by part, i just put the back plate off

Here's what we got:

Here's what we need:

You have to bend it until you have a litte square that can fits the SoC space but can have a little height



All right; Like the third photo: You have to put thermal grease on both SoC and Display Chassis, and put the square on the chassis or the SoC (better on chassis when assembling)...
View attachment 4053916
Carefully you reassembly the Motherboard starting with the upper zone, reconnect and DONE!!!!!
Results:
Before (With Thermal Grease):


After:


Information:

(Remember, This may o may not fix the problem at all; It can be temporal or not, depending the dissoldering status of the SoC/RAM)
(May 2023 Update: I replaced this phone for a PH-1, then a Xiaomi Mi 9, and now I have a Samsung Galaxy S20+; the G3 was dying anyways, so glad LG stop making unreliable POS devices)
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