[wooly]

checked both old batteries with a dry cell tester that applies some load. One battery was at 10% (2.06V) capacity, the other battery was 70% (2.62V)

Changed the battery this afternoon and checked the old one on a load tester and it initially showed 2.65v and dropped fairly quickly to 2.6v so I concluded that it is indeed rooted.
The new one measured 3.3v unloaded before I put it in, but I doubt it would stay like that for long.
Also cleaned the contacts in the clip assembly with isopropanol and a cotton bud for good measure.

The short battery lfe surprised me because my 20 year old Corolla still had the original battery in the fob when I sold it.

Thanks go to TerryT for an excellent diy guide to doing this without breaking something.

[Greyhound]

If you have the time, please let us know how you went.  Maybe a picture or two if the process is markedly different from the video?

I have no need to change battery just yet, just wanted to know how to do it in advance of when the time comes.
Yes I will post again if I can add more information to ths thread.

[TerryT]

If you have the time, please let us know how you went.  Maybe a picture or two if the process is markedly different from the video?

I have no need to change battery just yet, just wanted to know how to do it in advance of when the time comes.
Yes I will post again if I can add more information to ths thread.

@ Greyhound, ok, thanks, I understand.

[TerryT]

Changed the battery this afternoon and checked the old one on a load tester and it initially showed 2.65v and dropped fairly quickly to 2.6v so I concluded that it is indeed rooted.

Thanks go to TerryT for an excellent diy guide to doing this without breaking something.

"...it is indeed rooted."  I try to avoid using technical terms.

 Glad my guide was useful. 

[TerryT]

Below are two photos to help better illustrate Step 7 of my guide at post #290 of 4 August 2021.  I forgot to include them and cannot modify my original post to add them.

Step 7 (Modified)

(a) First, mate together the two ends of the fob (#1).  Use the thin lip on the case end to wedge into the other half.

(b) Firmly press the halves together in order #1~#3 until the halves click into place.   

[Greyhound]

OK I have finally been forced to change my flip-key fob battery as opening and closing the car had become troublesome.
I attach 3 photos which should be self explanitory. Just go easy working the case apart and don't go straight in with a flat head screwdriver or you will likely damage the plastic. You can carefully use a flat head once you have made initial separation. Enjoy.

EDIT: by the way I measured the old CR2032 battery voltage using my DVM and it was 3.0V. But even at that voltage the door open function was playing up.

[TerryT]

@ Greyhound.  Thanks for posting (above) your fob battery replacement guide, will be helpful for those with that style of key fob.