Belkin residential gateway w/ new battery not showing green "On A/C" light when plugged it

Update - looks like the answer is yes, the Belkin unit can no longer recognize A/C power and can't charge the battery.  After 5 hours the system failed.

Going to return the battery tomorrow for refund and find out how to get a new Belkin.

Any tips on getting ATT to bring a new Belkin without spending 75 minutes dealing with flow-chart techs telling me to "reset the router" 15 times would be appreciated!

Thanks again!

Not gonna happen.  Buy a proper UPS. 

Also likely if they still have that old gray UPS, they may have an old gateway as well.  Att might try to replace it if you call in. Doesn't sound like there's a pressing need unless you want to use something more recent for yourself. 

Thanks for your reply.  But "buy a proper UPS" may be an issue because ATT still insists (so far as I can tell) that the BU3DC001 is the only one they want them using with the services my in-laws have[1].  Or do you mean just go all private purchase?  I don't know what kind of deal my in-laws have set up - for all I know they might be paying some crazy monthly rental fee on the UPS and router/modem. My FIL would know but he's in the cardiac unit and kind of foggy right now.  

Thanks again for your reply.  I think I'll fix it now so at least when my MIL is at home she can get calls on the "home" phone and use the TV, and worry about removing rental fees (if any) later on when he's in condition to think about stuff.

[1] Unless it's been discontinued.  Doing a time-bounded search still drags in a lot of older results.

Yes, APC or whatever brand you prefer.  That Belkin has been dead for years.  Att doesn't supply that stuff for quite some time now. 

Also the U-verse TV product is on its last legs too and will need to be replaced at some point. 

Appreciate the guidance.