Finally I have solved the conundrum of the LG G5's GPS performance, and it turns out to be down to a mighty screw-up by LG. Messing with the contacts is a side-show, here is what's really going on, and the ultimate fix. I've been poking around this phone on and off for quite some time, and never been happy with the GPS behaviour, even after getting the best possible contact of that pesky spring to the pad in the back. Even with apparently reasonable signal strength (using the GPS Status app), the GPS fix data was still erratic. The position, speed, and particularly direction, would jump about. I noticed this especially when using the phone on my boat - it's a useful pocket navigation aid with the Navionics app which in particular shows a direction vector on the chart. On water your direction is the most important thing to know, and the vector would uselessly swing around all over the place. I never had that on any other phone. It all suggested the GPS signal reaching the receiver was very noisy, rather...

Hi Schlomsi, thanks for looking at this in detail, and validating most of what I found. In retrospect, I agree that my suggestion of the second contact relating to GPS is probably wrong. I had tried insulating this contact and failed to get a GPS lock, but I've re-tried it and this time it made no difference. It just shows how hard it is to reliably diagnose the problem! If you test continuity of the various contacts areas on the case with a simple multimeter, they do mostly appear to connect to ground - but that's just a DC measurement. At RF they will behave completely differently. I'm no expert on how these flat on-case antennae work, but they are likely cleverly etched tracks forming a pattern that matches the signal wavelength. If you look at a UHF TV antenna, it's usually a closed loop. I was interested when you said you'd tested the phone with the back off. I'd wanted to do that, but thought "how do you hold the battery in, and what about the power button?". So I revisited it, and found that a bit...

There are lots of posts and videos online telling you to tweak various contacts, but they're all wrong! I've finally fixed this after months of messing. 1. The GPS antenna is at the top-right, looking from the front of the phone. 2. The contact pad is a tiny piece of metal gauze at the very top right of the back. 3. There is only one contact on the main board that contacts this pad (easy to see which it is). I think the reason people say other things have worked is that simply opening and re-assembling the phone will re-seat the contact, improving performance for a while. Real problem: the contact gauze connects to the antenna at the top, the contact pin presses on it near its bottom edge. There should be a tiny rubber pad under the lower part of the gauze. This was missing on mine, so the spring contact never made good pressure on the gauze, and over time wore the gauze away. I only discovered this after buying a broken G5 on eBay and comparing. I swapped phone backs to get it working. I also proved this...