Instinct Solar 2 Battery Is Dying After 1 Year Of Light Usage

My Instinct 2 Solar's battery is draining at an alarming rate. It seems that the battery is dying. 

I have done a few hard resets (erased all data) followed by turning on the battery saver mode. Watch shows 65d of battery life. However, I am losing the battery is 3 days of battery per hour.

In short, 65days of battery life will be used up in about a day. 

In terms of settings, I have double checked VO2 , backlight and  other energy draining setting I can think, to minimise battery drainage.  Nothing works.  

I only had the watch for 1 year and a month. Does not charge my watch often - mostly about once every 25 days. Why is the battery almost dying with just less than 15 charge cycles? 

This is really ridiculous!

My software version is 11.18. 

I was told by Garmin's customer support to send my watch in for repairs. I hope that the repairs will not cost me a bomb. Otherwise, I will not buy Garmin anymore. 

I bought this Garmin watch because of its ability to integrate with my bicycle's Garmin sensors.  

I hope that my good impression on Garmin will not be ruined because of this.