Note 4 Won't Turn On, No Sign of Life

[E39BMW98]

I've been trying to figure out why my Galaxy Note 4 is not getting any power, but I just can't figure this out. I've tried letting it charge with a known good cable, booting it into recovery mode, and replacing the battery. I can't get it to turn on.
I checked the battery with a multimeter and it shows around 3.4 V. When I plug the phone in to a wall charger and test the battery contacts, I get about 4.8 V, so I know the phone is getting power (or at least the battery).
But unlike another Note 4 I have, this one won't show the notification light or anything. It doesn't show when I plug it into my computer, either.
What can I do to get it to turn on?

 

[natehoy]

This could be any one of a large number of things, starting with a wiring fault in the battery terminals that is not powering up some or all of the motherboard, right up to a motherboard that is fried. You could start by disassembling it and seeing if you can find any obvious fixable hardware faults.

iFixit has a really good writeup of the innards of the Note 4 - it is overall one of the easier phones to maintain. Some of the components are held together with adhesive but it's nowhere near as bad as most.

https://www.ifixit.com/Teardown/Samsung+Galaxy+Note+4+Teardown/34359

Short of starting to replace components in an attempt to fix it, if you cannot find any obvious hardware faults it's probably a goner.

 

[cadjak]

I've been trying to figure out why my Galaxy Note 4 is not getting any power, but I just can't figure this out. I've tried letting it charge with a known good cable, booting it into recovery mode, and replacing the battery. I can't get it to turn on.
I checked the battery with a multimeter and it shows around 3.4 V. When I plug the phone in to a wall charger and test the battery contacts, I get about 4.8 V, so I know the phone is getting power (or at least the battery).
But unlike another Note 4 I have, this one won't show the notification light or anything. It doesn't show when I plug it into my computer, either.
What can I do to get it to turn on?

You don't say if you were successful getting into recovery mode. Can I assume you were not? I have a couple of Note 4 phones that are in a similar state, One of them I can get to turn on if I leave the battery out for an hour, then put it back and it will boot. Obviously, that isn't a description of a phone that is very usable but it helped me to back everything up and move to a different Note 4.