Contact sensor

I installed this contact sensor in May. It’s on a door that is usually left open 24/7.

I started getting a low battery signal near the end of June. Ordered replacement batteries, installed and tried to pair. It kept timing out.

I removed the battery and reinserted it, times out.

I deleted the device and tried again, times out.

I removed and reinserted the bridge and tried again, times out.

Restarted the app and tried again, times out.

Cleared the cache and tried again, times out.

Tried another new battery, times out. I tried 3 other new Energizer batteries with I installed this contact sensor in May. It’s on a door that is usually left open 24/7.

I started getting a low battery signal near the end of June. Ordered replacement batteries, installed and tried to pair. It kept timing out.

I removed the battery and reinserted it, times out.

I deleted the device and tried again, times out.

I removed and reinserted the bridge and tried again, times out.

Restarted the app and tried again, times out.

Tried another new battery, times out.

Tried 3 other brand new Energizer batteries, same results.

BTW, it flashes 2 times when inserting the battery and flashes 5 times when inserting the pin.

Model: WHCS1

MAC: 777DE6F9

FCC ID: 2ANJHWHCS1

PURCHASED: March 27, 2019

ORDER #357274
IMG_20190728_115601 IMG_20190728_115656

This is an absolute longshot, but from the days of card edge connectors in computers I remember this trick. It looks like from your photo you might have some discoloration on your battery contact. Try a sharp edge or a pencil eraser and clean the contacts both sides and then try again with a known battery.
Good luck-remember I said it’s a longshot.