Download the APC UPS Daemon command line tool and use it to disabled the APC Back-UPS 550 alarm.
Note: This advice is based on software that was last updated in 2016 and I recommended in another answer back in 2020. I know I have successfully used it on macOS back in the “OS X” days in the past but haven’t in years. So hopefully this will work for you.
There is also a cool command line software called the APC UPS Daemon that can allow you to control an APC UPS from the command line easily without having to install the official PowerChute GUI software. It’s available for Mac and Windows as precompiled binaries as well as RPMs and Deb packages for Linux in addition to pure source code that you can compile an pretty much any system.
This blog post from 2012 does a decent job of explaining specifically how to use the APC UPS Daemon software to disable alarms. Here is the command line flow once you get the APC UPS Daemon software software installed and apctest
is available:
sudo apctest
2012-11-18 23:30:50 apctest 3.14.8 (16 January 2010) debian
Checking configuration ...
Attached to driver: usb
sharenet.type = DISABLE
cable.type = USB_CABLE
You are using a USB cable type, so I'm entering USB test mode
mode.type = USB_UPS
Setting up the port ...
Hello, this is the apcupsd Cable Test program.
This part of apctest is for testing USB UPSes.
Getting UPS capabilities...SUCCESS
Please select the function you want to perform.
1) Test kill UPS power
2) Perform self-test
3) Read last self-test result
4) View/Change battery date
5) View manufacturing date
6) View/Change alarm behavior
7) View/Change sensitivity
8) View/Change low transfer voltage
9) View/Change high transfer voltage
10) Perform battery calibration
11) Test alarm
12) View/Change self-test interval
Q) Quit
Select function number: 6
Current alarm setting: ENABLED
Press...
E to Enable alarms
D to Disable alarms
Q to Quit with no changes
Your choice: Select function: d
New alarm setting: DISABLED
1) Test kill UPS power
2) Perform self-test
3) Read last self-test result
4) View/Change battery date
5) View manufacturing date
6) View/Change alarm behavior
7) View/Change sensitivity
8) View/Change low transfer voltage
9) View/Change high transfer voltage
10) Perform battery calibration
11) Test alarm
12) View/Change self-test interval
Q) Quit
Select function number: 6
Current alarm setting: DISABLED
Press...
E to Enable alarms
D to Disable alarms
Q to Quit with no changes
Your choice: Select function: q
1) Test kill UPS power
2) Perform self-test
3) Read last self-test result
4) View/Change battery date
5) View manufacturing date
6) View/Change alarm behavior
7) View/Change sensitivity
8) View/Change low transfer voltage
9) View/Change high transfer voltage
10) Perform battery calibration
11) Test alarm
12) View/Change self-test interval
Q) Quit
Select function number: q
2012-11-18 23:32:59 End apctest.