APC Back Ups RS 1500G-IN LED display goes off and showing 1-2 minutes backup

[BillP]

My APC BR1500-IN is more than 3 year old.... I did replace my batteries 8 months back, I replaced the 9ah battery with Genuine Amaron 7.5ah .... it performed good for 3 months but after 3-4 months the backup is just 5-6 minutes... 

all of sudden one morning I saw its led display got dimmed and hardly visible and after a few days is not showing anything .. i have checked everything like display power saving , hard reset etc but no luck...
Sometimes after switching off ups for few hrs it again shows display but it starts dimming gradually and goes off eventually..

Now the status is, my battery power is showing 1-2 minutes in PCPE (even disconnecting usb doesnt work) and led display is off (will appear after switching off power)

Tried following steps:

1. Hard reset (unplugging ups, disc all loads, take out battery, pressing ON button for 10 secs etc)
2. Tried changing battery replacement date
3. Disconnecting usb cable 
4. tried charging ups without any load 

and many more but nothing working .... it is my 2nd UPS of 1500va which i bght in years 2016 .. earlier i had older model of same ups which also worked for 2 years only then the same battery problem appeared , wasted lot of money on new batteries many times but didnt work... it worked only for 2-3 months then no backup..... 

I think APC ups are meant to use for only 2 years max then we have to throw it... I am now planning to buy some other better ups tht shld work for at least 5-6 yrs...