[LG K20 Plus Questions & Answers] HelpNeededPlz:
Hi, I have a LG K20 Plus. I currently can't turn the phone on, so I don't have much software information to give you. The phone was bought at T-Mobile (Metro by T-Mobile) and I had a SafeLink sim card and a 16 gb micro sd card inserted when the issue started. I have since removed both. It says Qualcomm snapdragon on the screen when it starts. It was also rooted and the bootloader is unlocked.

I broke the screen on my phone and I decided to do the repair myself. I have done about 7 or 8 screen replacements and I actually did this phone a year ago with no issues, so I felt I could manage this one as well. I bought an entire display (from ebay) and switched it out with no problems. Initially it worked great! I used it for a few days before realizing that I had no sound. I opened it back up and noticed the loud speaker had fallen out. I found it, put it back in, reassembled it as I normally do and turned it on.

NOTE: when I was reassembling it the second time, I actually tried to put a screw in a hole that wasn't a screw hole. I used a light to normal amount of pressure but I didn't force it. I think it's the hole where the moisture detector is. Picture #1

I turned it on and right after the logo screen I got a message that said "High temperature detected Powering off for your safety" and it immediately shut off. The phone does appear to charge normally but it won't stay on. I did a factory reset (I'm not sure if it's still rooted but the bootloader is still unlocked). I also switched back to the old (broken) display just to check if that would work. I couldn't see any difference in the shielding but I switched them just to be sure. I bought a new battery and installed it. I took a q-tip and 95% Isopropyl Alcohol and cleaned pretty much the entire motherboard, paying special attention to the battery connections. After each one of these things, I tried to start it with the same error message immediately upon start up.

NOTE: At no point has the phone every physically felt hot or even warm. I don't think it's on long enough for it to get hot. But something is wrong and I have no idea what it is. I, literally, took the phone apart, put in the speaker and put it back together in less than 5 minutes. Could it be I just bumped something and knocked it loose?

I searched for any information I could find both here and with google but there is next to no information on the LG K20 Plus. I did find some information on the LG V20 that had overheating issues, and that has been all the luck I've had. I watched several videos and it seems the solution is to apply thermal paste. But my phone doesn't have any evidence that thermal paste was ever on it. I went and bought some but I have no idea where exactly to put it or even if it's needed. Most videos showed people using some kind of aluminum foil but I'm not sure if that is safe. I have several old phone laying around and I managed to get some of the silver tape and a copper square thing but, again, my phone did not have these things to begin with. I don't want to start adding things only to make it worse.

There is a slight difference of the tape that is on my phone now (the display I just bought) as compared to the old one (broken display). Picture #2 Again, I have no idea if that means anything but I thought it worth mentioning. Picture #3 is how it looks now as if I were going to put it back together. Picture #4 is the part (don't know name) where the videos show to apply the thermal paste and the shielding.

I'm really at a loss as to what to do next and I can't really afford to take it in to have it repaired before next month. If anybody has any insight or answers as to what happened, I'd be very grateful for your help. I'm sorry for the long post. I just wanted to tell you everything I have done in detail. Thank you