Phone Not Charging, which parts should I check/replace?

Hi Corwin,

Okay, we're going to start with the assumption that you've tried the obvious fixes external to the phone, including using a different charger, swapping out the cable, and cleaning the charging port.

Once you've gotten those eliminated as the. source of the problem, we have to conclude the issue is inside the phone. In there, we've got like four components to consider; the charging port itself, the cables connecting the charging port to the motherboard, the motherboard itself, and finally the battery.

Given the design of the phone it does appear there's one connector that could conceivably come loose; that's the lower plug on the interconnect cable between the daughter card and the motherboard, so you could open up the phone and check that as a first step.

With an intermittent issue like yours, the most likely place to start for me would be the charging port. That's the part exposed to the outside world, and is subject to wear or damage from being plugged and unplugged, especially from stress when a cord is plugged in. iFixit only has a guide for replacing the entire charging port, but apparently it's not too difficult to remove the USB-C port from the daughter card once it's out. Here's the iFixit guide.

OnePlus 3 Daughterboard Replacement - iFixit Repair Guide

On the other hand, there's a French site called SOSav that has an actual guide for just the USB-C port. It is, of course, written in French, but if you use it with the Chrome browser, the automatic translation works great and makes it quite usable.

Charging connector / Microphone OnePlus 3 repair - Free guide - SOSav.fr

The part itself looks pretty easy to get; I usually check the big three to start with; Amazon, eBay and AliExpress. Here's one of the first ones that came up on Amazon.

Amazon.com: ePartSolution Micro USB Charger Charging Port Dock Connector Ribbon Flex Cable Replacement for OnePlus 3 OnePlus 3T A3003 Replacement Part USA : Cell Phones & Accessories

That's where I'd start; replace the port then reevaluate. If for some reason that doesn't do the job, the next step would be the interconnect cable right next to the charging port cable would be worth a try.

OnePlus 3 charging connector cable repair - Free guide - SOSav.fr

From there, about the only thing left would be the battery itself; it doesn't really sound like the issue with your phone, but if you've replaced the two previous parts then other than the daughter card itself, that's all that's left that you could fix yourself. The motherboard should be saved for last, since board level repairs on phones requires equipment and expertise generally pretty far beyond us home DIY-ers.

To sum up, I'd check the connectors first, then replace the charging port and see where you are. Try that then come on back and let us know what you've found and if that fixed it or not.