So here are latest results.
With unit off, on first pre-boot, I can load sw 6.40 boot.bin only rgn, I see LOADER LOADING...SOFTWARE LOADING... then I see LOADER. Try to load fw_all only, get error "unable to program requested memory region" unit reboots. Then I use G7toWin GPS>Commands>Power off, unit reboots, hold top/left to get into pre-boot, now fw_all.bin only flashes successfully (~1min) with LOADER LOADING on screen. Now I can flash boot.bin only afterwards successfully (~3secs) on screen seen as above. Then I do G7toWin power off. Unit restarts into looping with logo white screen. I did verify region 14 does chance. No change to 5.