Back button & light button not working (reopened)

The Fenix 8 has changed the button technology, they should be truly waterproof (no seals, induction through the housing) even though they seem to have calibration issues now lol.

I also had my F7 exchanged because the back button was randomly activating or getting stuck, so now I've decided to rinse it frequently but never go swimming again with the watch, and hope it won't happen again...

You are not unluckly, Fenix 7 and Epix have bad button quality making those watches likely to fail when used in water, and in some cases even when not used in water at all. As meuhbat said, Garmin decided to change buttons on Fenix 8, and it is no wonder why, but it is interesting that Garmin never gave official statement about this problem and even released Fenix 7 Pro and Epix Pro with same issue.  

As you noticed, this was not such common issue in Fenix 5 for example, which clearly shows that Fenix 7 quality is inferior. Other long-time Garmin users have had same experience. 

Here are few more threads about it:

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/epix-2/309478/epix-2-problem-buttons-light-and-back-lap

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/epix-2/351644/garmin-epix-2---buttons-stopped-working

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/342939/back-button-issue-after-sup-paddle-session

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/339981/fenix-7-start-stop-button-stopped-working

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/322610/fenix-7-sapphire-solar-button-issues-mainly-the-back-button 

Vizi said:

Garmin decided to change buttons on Fenix 8, and it is no wonder why

They changed the buttons to a non-penetrating induction type in order to enable the buttons to be pressed at depth for the dive functionality. The dive functionality needed for the Fenix to compete against the Apple Watch Ultra 2. Garmin already had the design available with the Descent so it was probably somewhat trivial to move the tooling over to the new case.

The issue that the OP is discussing seems to relate to grit, oil or some combination being trapped under the button which no longer allows it to be compressed (seems to happen with ocean swimming or with folks who frequently wear suncream / sweat). Not sure if the new button style with allow for that to clear any more easily as I haven't seen a teardown. I'm also not confident enough in yours or my own opinion on the matter to call it resolved or still an issues.

Anyway, none of this helping to poster get his issue fixed. The only thing he can really try and do is clear the debris with warm soapy water or failing that, unscrew the back of the casing to access the buttons. I've done both recently and it's really quite trivial.

Vizi said:

As you noticed, this was not such common issue in Fenix 5 for example, which clearly shows that Fenix 7 quality is inferior

I wouldn't jump to such a conclusion unless you know how many Fenix 5 and 7 units were sold and how many had the issue. Whats your definition of "common"? 1/10000? 1/100?

I've had both the Fenix 5+ and 7 and I can tell you that my 5+ experienced a jammed button almost every 3 months necessitating a soak as I was surfing every weekend. On the Fenix 7, only once, but then again I'm not surfing as frequently.

These anecdotes mean little as only Garmin know what the return and failure rates are. I wouldn't be as comfortable making such sweeping generalisations.

2529455 said:

Apple Watch Ultra 2

No sure what's different in the AW2, but I guess it's just the nature of having mechanical buttons: there are tons of posts around various forums about stuck side/action button and the mushy crown on apple watch and apple watch ultra, which exhibit quite similar problems as Garmin.

On my previous fenix 5 the back button was half stuck (always fixed with some cleaning and drops of silicon oil), but the 7X pro is running perfect after a year and a half. Not doing any specific water sports though.

OP asked if he was the only one with that issue, and I replied that he is not only one and that these watches tend to fail after using in water, sometimes even when not used in water, with threads that confirm my argument. 

Your long post does seems more like and effort to downplay the issue and hide the fact that other users had exactly same issue rather than to help the user or answer his questions. 

Thank you all for chipping in, I think I got the picture.

About the water. I am not a swimmer, so it was not an issue, but I do sweat. Is there a trick to run a half marathon, or play tennis for 2 hours, and not sweat? ;-) If avoiding sweat and water is the solution, it is equal to not have the watch.

@2529455, I was thinking about taking the back off and clean the button, too, but was a bit afraid of not being able to put the seal back properly, and, well, why bother if Garmin replaced the watch. ;-) You gave me hope that it works, I will try and do it. Thanks for the idea!

In my fury, I actually just bought an Apple Watch Ultra 2, let's hope it will last. From what I am reading here, it could be a hit and a miss, too.

I do sweat a lot too, and my main activity is running (just done a relay marathon yesterday), plus other outdoor activities like mtb and occasional other outdoor activities. I remove the watch only for charging, otherwise is always on my wrist, so I'm pretty sure sweating it's not the cause of this stuck buttons. They are not even in direct contact of the skin. Also in winter I use it over the jacket, and when it rains it gets very wet.

Maybe they changed something in the Pro (I have the 7x PRO solar) to make it less prone to this problem, not sure, but replacing the watch 4 times it looks like it could be something else. I'm thinking maybe you do live in a very dusty climate, or you do a job where you often are in contact with small particles from debris, maybe wood cutting, or chemicals from paint etc? Maybe you are out for fishing often and the watch get constantly submerged in not very clean water, etc, you get the point..

Holly cow! I fixed it! :-)

Firstly, it is not the back you have to take off, but the bezel (the front), disconnect all the connectors, including the battery connector, and then the main board comes off easily.

As you can see at the top of the picture, the buttons connect to the main board with little "flapping" brass connectors, two connectors each button. I tested the middle button with a multimeter, and when the button was pressed, the two connections were shorted. And I didn't have to press it hard at all!

If you look at the close up below, you can see these brass connections have to press against the edge of the main board, and in my case, they looked pretty flat.

So, I just bent them a little bit outward, put everything back as they were, and the middle button works perfectly.

So, in my opinion, it is not dirt or sweat that causes the problem, but metal fatigue, you could say low quality material used for the brass connectors. :-(

And I can kind of see how that problem is "addressed" by pressing hard on the button. You pretty much bend the whole case, just a little bit, so that the brass connectors make connect with the edge of the board, just enough.

Nice that you fixed it.

Have you looked at how the sealing is made around the button? Do you have pictures?

In my case the button was activating itself randomly, there was probably some water involved in here.