some big letdowns right away and very slow progress

[bicameralmind]

The dd command is right (if X is right), but,but,but
For images (or other large files), flash does not like writing (default) bs=512....(bytes)
Very slow (10x), probably write multiplication
_I_ always use bs=1M  <- M not m, some dd's choke on 1m
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I assume you have decompressed image? If it is a xz or gz??
Or a pipline,,, xzcat xz_image | dd of=....  bs=1M status=progress
(zcat for gz images)
To see inside an image, you have to loop mount it (or write it to media)
mount requires an appropriate offset (In bytes, use fdisk to get sectors)
sudo mount -o loop,offset=..... some_image mount_point (must be uncompressed image)

I get as far as this page https://www.gnu.org/software/coreutils/m...invocation and I bog down because still too much jargon on my level. Should I try the jumpdrive route on the old windows machine? I guess I could also plug a keyboard and monitor into the phone if the cropped display won't happen, really helping me to actually see what I am doing, but as I hear often now, "I think that is a software problem." haha. It is a live OS so of course it will look bad on a big monitor, right? 

So, no, you did not really help me yet except for TRYING--thank you! Just a bit more plain speaking, cheers.