Service manual my ups tripping while main power drops, not going to ups mode pls help me regarding this

Those units come with a battery life of apron 2 to 3 yrs. Even at three years, it only take one bad battery out of all the batteries in the unit, for the UPS to fail. The batteries are tied in series. You might find the batteries cost $10.00 to $25.00 per batteries, depending on how many you have. But some times its best to just buy a new UPS. Or if you want you can infall them your self. Its fairly easy, but be very careful you don't short out the batteries if you install them or one backwards. Those units come with a battery life of apron 2 to 3 yrs. Even at three years, it only take one bad battery out of all the batteries in the unit, for the UPS to fail. The batteries are tied in series. You might find the batteries cost $10.00 to $25.00 per batteries, depending on how many you have. But some times its best to just buy a new UPS. Or if you want you can infall them your self. Its fairly easy, but be very careful you don't short out the batteries if you install them or one backwards.