Recovering ramips: TEW-810DR

I ended up with a minimally responsive device after flashing a snapshot to a TEW-810DR
https://openwrt.org/toh/trendnet/trendnet_tew-810dr_1.0_1.1

cat /proc/mtd

dev: size erasesize name
mtd0: 00800000 00010000 "ALL"
mtd1: 00030000 00010000 "Bootloader"
mtd2: 00010000 00010000 "Config"
mtd3: 00010000 00010000 "Factory"
mtd4: 00010000 00010000 "5G_RF"
mtd5: 00010000 00010000 "Wolf_Config"
mtd6: 00080000 00010000 "MyDLink"
mtd7: 00080000 00010000 "Jffs2"
mtd8: 000f8ebc 00010000 "Kernel"
mtd9: 00597144 00010000 "RootFS"

The snapshot firmware had a partition that was subsequently reset.
https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=6b7a525a725a78ff961d91a76e4ea9fbb7066178

I can "reset button" and enter an Emergency Flash web interface at 192.168.10.1, browse to the latest factory/OpenWRT firmware but it does not upload. I 've tried nobody:nogroup the firmware.

I've ordered a USB Serial TTL interface but there is a raft of varying examples and none that I could find specific for Trendnet. At this point I do not have much to loose and could learn something Any pointers appreciated.