@RonS the problem with this device is that triggering EDL mode with the UFED cable won't work for some reason, so the only option remains shorting the emmc
@UnallocatedClusters I can confirm that shorting the emmc triggered a fault signal and at the next connect the device went to EDL mode. It is very confusing, because the device screen remains black, like nothing would happening.
@RonS the problem with this device is that triggering EDL mode with the UFED cable won't work for some reason, so the only option remains shorting the emmc
This was actually considered a security hole and patched by lots of vendors in recent firmwares couple months back so it's even impossible to reboot to edl mode from fastboot (this was a thing for Xiaomi devices) or from working system via adb and testpoint is the only option. From my experience, booting LG (and Huawei) into EDL using only a cable rarely worked anyway.
It is patched in newer devices and newer chipsets.
It does work for 100's of other models including the M153.
Shoring eMMC is simpler than a chipoff or ISP/JTAG, so worth trying.
RonS
For some models there are two EDL testing points, just usually without marks. Shortening those also makes the phone boot into DEL mode next time.
@RonS true, entering the EDL is way easier then any chip-off/JTAG/ISP, but the real "power" of the factory mode is being able to "read" the encryption keys from the Trusted Zone for almost any Qualcomm based device and make a decrypted acquisition on the fly directly from the device. Some say it's a security hole, but I look at it as a backdoor left there on purpose )