When you refer to shutting down all devices what are you refering to? I am new to all this. Also the battery for the APC was $80.00 plus $10.00 shipping and the new Philips was only $32.00 shipped. I did what worked for my pocket.
Fair 'nuff. I understand such circumstances only too well.
Shutting down devices: I take it you've got a number of devices connected to your present APC UPS (oh lawdy, all these acronyms).
1. You need to shut them down one-by-one, just make sure that you've saved any work in progress on your computer.
2. Then disconnect all power cables from the UPS. ie. pull the plugs.
3. Switch off and unplug the UPS from the wall socket. That will cause its battery to kick in but that doesn't matter because you've got nothing connected to it anyway. You can discard that APC (but see later).
4. Plug your new Philips unit into the wall socket - but
make sure you've read the instructions about First Use, because there is a correct procedure to follow eg. the order in which you switch things on and connect devices etc.
The APC unit - as I said earlier, that brand is an industry leader with superior battery technology, which is one reason why their stuff is more expensive. In due course, and it's entirely over to you, you might consider replacing the battery and perhaps selling the unit to defray the costs, perhaps even replacing the Philips with the refurbished APC.