[General Questions and Answers] clsA:
Good morning, I watched the video and I'm not sure whats going on with the ghost touch. It seems to be in a pattern of some sort so it may be totally normal.

As for returning to stock with the LGUP Dump. Its a matter of fastboot flashing each of the partitions back to the phone one at a time. It is possible to create a ROM that's flashable with TWRP or a batch file to flash in fastboot. I'll try and find something for you to use as a template or a good example.

Alright here's the Back to stock Rom script for the LG V20 20H > https://www.androidfilehost.com/?fid=1322778262904015326

the file is found here in the root of the zip \META-INF\com\google\android\updater-script"

ui_print("Flashing H910_20h_Oreo_full_stock");
ui_print("Please wait...");
ui_print(" ");
package_extract_file("aboot", "/dev/block/bootdevice/by-name/aboot");
package_extract_file("abootbak", "/dev/block/bootdevice/by-name/abootbak");
package_extract_file("apdp", "/dev/block/bootdevice/by-name/apdp");
package_extract_file("boot", "/dev/block/bootdevice/by-name/boot");
package_extract_file("cmnlib", "/dev/block/bootdevice/by-name/cmnlib");
package_extract_file("cmnlib64", "/dev/block/bootdevice/by-name/cmnlib64");
package_extract_file("cmnlib64bak", "/dev/block/bootdevice/by-name/cmnlib64bak");
package_extract_file("cmnlibbak", "/dev/block/bootdevice/by-name/cmnlibbak");
package_extract_file("devcfg", "/dev/block/bootdevice/by-name/devcfg");
package_extract_file("devcfgbak", "/dev/block/bootdevice/by-name/devcfgbak");
package_extract_file("factory", "/dev/block/bootdevice/by-name/factory");
package_extract_file("hyp", "/dev/block/bootdevice/by-name/hyp");
package_extract_file("hypbak", "/dev/block/bootdevice/by-name/hypbak");
package_extract_file("keymaster", "/dev/block/bootdevice/by-name/keymaster");
package_extract_file("keymasterbak", "/dev/block/bootdevice/by-name/keymasterbak");
package_extract_file("laf", "/dev/block/bootdevice/by-name/laf");
package_extract_file("lafbak", "/dev/block/bootdevice/by-name/lafbak");
package_extract_file("modem", "/dev/block/bootdevice/by-name/modem");
package_extract_file("msadp", "/dev/block/bootdevice/by-name/msadp");
package_extract_file("persist", "/dev/block/bootdevice/by-name/persist");
package_extract_file("pmic", "/dev/block/bootdevice/by-name/pmic");
package_extract_file("pmicbak", "/dev/block/bootdevice/by-name/pmicbak");
package_extract_file("raw_resources", "/dev/block/bootdevice/by-name/raw_resources");
package_extract_file("raw_resourcesbak", "/dev/block/bootdevice/by-name/raw_resourcesbak");
package_extract_file("recovery", "/dev/block/bootdevice/by-name/recovery");
package_extract_file("recoverybak", "/dev/block/bootdevice/by-name/recoverybak");
package_extract_file("rct", "/dev/block/bootdevice/by-name/rct");
package_extract_file("rpm", "/dev/block/bootdevice/by-name/rpm");
package_extract_file("rpmbak", "/dev/block/bootdevice/by-name/rpmbak");
package_extract_file("sec", "/dev/block/bootdevice/by-name/sec");
package_extract_file("tz", "/dev/block/bootdevice/by-name/tz");
package_extract_file("tzbak", "/dev/block/bootdevice/by-name/tzbak");
package_extract_file("xbl", "/dev/block/bootdevice/by-name/xbl");
package_extract_file("xbl2", "/dev/block/bootdevice/by-name/xbl2");
package_extract_file("xbl2bak", "/dev/block/bootdevice/by-name/xbl2bak");
package_extract_file("xblbak", "/dev/block/bootdevice/by-name/xblbak");
ui_print("Now installing system -- please wait...");
package_extract_file("system", "/dev/block/bootdevice/by-name/system");
ui_print("Enjoy The Update");

To restore your modems you need to add this to the above script

package_extract_file("modem", "/dev/block/bootdevice/by-name/modem");
package_extract_file("modemst1", "/dev/block/bootdevice/by-name/modemst1");
package_extract_file("modemst2", "/dev/block/bootdevice/by-name/modemst2");
package_extract_file("fsg", "/dev/block/bootdevice/by-name/fsg");

Hint: you must use a text editor like Notepad++ if you edit the file.

Hint: it's actually easier to download the above Rom and just replace the files in the zip with yours

Your zip may not contain everything in the above zip. you can edit it as needed.