CE0537 N2965 chest strap battery - Polar S150 Heart Rate Monitor

Try to humidify contact area on chest strap(each side front). Also batterie weak in strap?

You can find them on amazon, here: Finally charging for our multi device world. Have a nice day

If the EFX 544 has polar Heart Rate attach to the upper electronics your chest strap should be transmitting and the unit should be receiving. If your chest strap is more than 3 yrs old usually the battery will die and needs to be replaced or you have a defective receiver and will have to be replaced

You certainly have had good service out of the battery. It is best left to a watch repairer to replace the battery.

Hmmm. Trick one without seeing the unit.. The most obvious is that the battery in the chest strap is dead. If it's one of the sealed ones then the whole chest strap will need to be replaced, if not then it'll be a standard watch battery. I should be clear from the chest strap if the battery can be replaced.
If both batteries are ok then try to turn on the Forerunner, put on the chest strap(make sure to lick the back of the sensor or dip it in water to make a solid connection, strange I know but that's what they reccomend). Then hold your wrist wearing the Forerunner a couple of inches from the sensor on your chest, sometimes needs to be for 30 seconds or so.. All going well that should do it.. Beyond that you're into the software in the Forerunner itself and that has to go back to Garmin..

Had the same problem. Just figured it out. The center Polar Logo on the strap needs to touch your chest in a firm way. Bend it back slightly so it fits snug on the middle of your chest.

I' advise to start with battery check. If the battery is ok, then you will need a professional to find the cause of malfunction.

A HRM is a training tool that helps you do cardiovascular (CV) training correctly, neither too hard, nor too easy. It’s almost like having a personal coach on your wrist! Every HRM comes in two parts: 1. An elasticated chest strap which contains a pair of sensors that detect and transmit your heart rate. 2. A wrist worn receiver that receives the signal from the chest strap and displays your heart rate. The receiver may also have additional functions and display other information depending upon the HRM model chosen. Both the chest strap and receiver are battery operated.

Nike Triax CV10 - Successful HRM reset 7 November 2008
 
I had real problems too. Even after repeatedly following the known reset steps everyone else is posting up. Here’s how I got mine going, please forgive the mind bogglingly tedious detail…
 
First make sure you’re using new good quality batteries. I used Maxell’s, bought in 10’s from Hong Kong on ebay – no problem.
 
Second, and this is the ESSENTIAL bit…move right away from the computer and any other electromagnetic sources before carrying out the known reset…
 
Third, follow the known reset steps below, adjusted to what worked for me…
 
If you press all four buttons of your Nike HRM it will reset. Next time you go to "RUN" mode, it will show "HRM LINK" error. You will now need to "hard reset" the unit.
 
Nike made a late change to add a "hard reset" to the chest strap. To re-link (re-initialise) the watch you'll need to open the battery door on the chest strap, and use a paper clip (or the equivalent) to push the small gold button in the battery area. There should be a small sticker in the battery compartment that points to the reset button.
 
The re-initialisation steps for the Nike C10 and CV10 digital HRM's is:
 
(1) reset the watch
(2) open the battery door on the chest strap
(3) move the watch to RUN mode
(4) press the reset button in the chest strap battery area without removing the battery
 
Tip - I agree with the suggestion to use a pin or needle and definitely do it with the battery in the hrm.
Tip – Thumb holds battery to stop it from pinging out, other hand performs jiggle with pin until the link is made (it links straightaway if you jiggle it just right!)
 
(5) replace chest strap battery cover…and smile!

If you can't link the hrm do as detailed in the following link If you press all four buttons of your Nike HRM it will reset. Next time you go to "RUN" mode, it will show "HRM LINK" error. You will now need to "hard reset" the unit. Nike made a late change to add a "hard reset" to the chest strap. To re-link (re-initialise) the watch you'll need to open the battery door on the chest strap, and use a paper clip (or the equivalent) to push the small gold button in the battery area. There should be a small sticker in the battery compartment that points to the reset button. The re-initialisation steps for the Nike C10 and CV10 digital HRM's is: (1) reset the watch (2) open the battery door on the chest strap (3) move the watch to RUN mode (4) press the reset button in the chest strap battery area (5) put the battery back in the chest strap (if it's not already in - it's possible to push the button without removing the battery) (6) hold both of the electrode to create a signal (probably not necessary - it usually links immediately). My suggestion is to use a very thin needle and do it with the battery in the hrm. Eventually, Nike will either eliminate the hard reset or update the manual to include this info.