I have three between home and work, the two Belkins cost me about $400.00 each from memory and both died at about 4 years old, I got new batteries ( 2 in each ) for about $40.00 each I think. Remember if you replace the batteries yourself you are playing with very hight voltages be very careful, they do output 240V.
And yes I thought I had a blown fuse or something too as they suddenly died but new batteries have them back good as gold again