A button has been jammed

If you guys needed an answer still,

I used a bit of bluetack pressed down hard on the button and it managed to pull the button out.

Hope this helps.

Not a long term fix but works short

It is VERY easy to open this watch. The battery and button contacts are attached to the back plate. Only four little screws to remove once the strap has been removed. I suggest opening, careful cleaning, and checking of contacts. Then re-assemble. See here for how to open:

Polar M400 Watch Battery Replacement

Hi Patrick, if you feel confident enough, this is what i did to free up the buttons. Removed the outer case, you’ll need star screwdrivers, then undid the circuit board screws ( Philips-head) and removed the unit completely for access, I didn’t bother to disconnect the battery. Once out I have a Jewellers eye glass as the parts are exceedingly small. Depressed the sticking button and removed the small securing clip holding the button in place. Make sure you’re doing all this on a white linen cloth as the parts are very easy to lose. Once the clips removed the button comes out. There you’ll find a metal washer, a rubber gromit and a small spring. I just gave everything a clean and the spring a slight stretch before putting everything back in reverse.

the tools I used were:

Star screwdriver

Philips-head screwdriver

thin nosed tweezers

A cup to hold the screws

Jewellers eye piece

let me know if this helps.

Michael

I wasn’t keen on opening it up. I’ve had the bottom left button jam twice and each time I’ve used beard trimmer oil and it’s sorted it out after a few hours.

I had the same problem with my M400 watch. The top right button was jammed.

My solution was this: open the watch and remove the pcb and everything from the inside. Take some tweezers and dip them in a fine mechanics oil (Ballistol for example, or any thin oil that doesn't harden. But please no WD40!). Then push the button and apply the oil on the pin that pushes the contact on the pcb. Try to press the button some times until it goes smoothly. Than reassamble the watch. Be careful: collect any drips of oil before the assembly.