[Upgrading, Modifying and Unlocking] callihn:
Disclaimer: I nor XDA nor anyone else is responsible for your lack of reading or comprehension skills, ignorance on your part or anyone else's nor just plain stupidity on your part or anyone else's, so if you don't know what you're doing and or don't know how to fix any bad things that could happen then just don't do it.

Root and Busybox required.

This is a more permanent solution to stop OTA updates from downloading on your rooted device that is designed to survive when you wipe /cache. I'm including the script which will work on any device that downloads it's OTA updates as update.zip to /cache without modification and a flashable zip, the flashable zip is for the LG K7 m1 Metro PCS variant rooted with Magisk ONLY (unless modified) and was fully tested, you're free to edit the script and or the updater-script in the flashable zip for your device (be sure you get the /system partition for your device right, the init process right if not rooted with Magisk and the proper location and file name for your OTA updates) and you may release it for others to use if you like but please give appropriate credit. The script can simply be dropped in your appropriate init folder (/data/adb/service.d/ for Magisk) and set chmod 0700 before rebooting your device.

Alternately you can use MacroDroid to run the script at boot.

Trigger > Device Events > Device Boot

Action > Applications > Shell Script (Paste script on line)

The rest should be self-explanatory.

Thanks to QuickNET Tech for coming up with this method. You can and should read about it HERE and follow up with part 3 from their post so you don't get the annoying notifications. Instructions for reversing this modification are also in that thread, in addition to those instructions you'll also need to delete the 22otakiller script from your init directory (default is /data/adb/service.d/).

What this script does:

The script (see bottom of this post) when ran either automatically on boot or manually will check for update.zip in /cache, if it exist but wasn't created by the script or using the same method with the appropriate attribute applied then it will delete it (regardless of size including an authentic update.zip file) and create the appropriate 0 byte update.zip file with the appropriate attribute and permissions, if it doesn't exist it will create the appropriate file with the appropriate attribute and permissions. It creates a 0 byte update.zip that can not be modified or deleted by anyone including the super user without removing the file attribute which can only be removed by the super user. The flashable zip for the LG K7 rooted with Magisk ONLY (unless edited for your device and or root method) will install the script to /data/adb/service.d/ and set it's permissions to 0700.

Please let me know and post your device information if the updater-script in the flashable zip works as-is with your device.

Enjoy!

Script (22otakiller):

#!/system/bin/sh
uzip="/cache/update.zip"

if [ -f "$uzip" ] && lsattr "$uzip" | cut -c 6 | fgrep -q 'i'
then
exit
elif [ -f "$uzip" ]
then
rm -f $uzip
touch $uzip
chmod 7400 $uzip
chattr +i $uzip
exit
else
touch $uzip
chmod 7400 $uzip
chattr +i $uzip
exit
fi