At scripts/dump.sh:22 the address given is 0x889EA000 but when I try that I get an error:
ERR(../drivers/usb/gadget/v2_burning/v2_common/optimus_download.c)L694:imgSz 0x889ea000 out of cap 0x859ea000
I tried changing address to 0x859ea000, and the resulting file appears to be a valid ext4 filesystem, and is mountable without errors, so I think that might be the right address to use.
cheers