Disable beep of KSTAR Powercom 600VA UPS (USB identifies as MEC0003)

I got it working with Network UPS Tools (NUT)

Configuring NUT for KSTAR UPS

$ sudo apt install nut nut-cgi

Sudo edited /etc/nut/ups.conf to contain:

# Set maxretry to 3 by default, this should mitigate race with slow devices:
maxretry = 3

[kstar]
driver = nutdrv_qx
port = auto
desc = "Description of this UPS"

and sudo edit /etc/nut/upsd.users

[admin]
password = youradminpassword
actions = SET
instcmds = ALL

Finally, sudo edit /etc/nut/nut.conf and ensure MODE is set to standalone:

MODE=standalone

Start up the ups driver and NUT deamon:

$ sudo upsdrvctl start
Network UPS Tools - UPS driver controller 2.7.4
Network UPS Tools - Generic Q* USB/Serial driver 0.28 (2.7.4)
USB communication driver 0.33
Using protocol: Q1 0.07
Can't autodetect number of battery packs [-1/13.70]
Battery runtime will not be calculated (runtimecal not set)

$ sudo systemctl start nut-server

Checking beep status

To see current beep status, use the upsc command:

$ upsc kstar
Init SSL without certificate database
battery.voltage: 13.70
device.type: ups
driver.name: nutdrv_qx
...

ups.beeper.status: enabled

...

Disabling beep

Use the upscmd command with the username and password you configured in /etc/nut/upsd.users:

$ upscmd -u admin -p admin kstar beeper.toggle 

and we see that beep is now disabled

$ upscmd -u admin -p admin kstar beeper.toggle 
OK

$ upsc kstar | grep beep
Init SSL without certificate database
ups.beeper.status: disabled

It might take a second or 5 for upsc to reflect the status change. Voila, no more beeping when the AC is down.