Off the top of my head:
Plug an ethernet cable into non-wan port (this might not even matter...) - connect it to your network.
I used 'game' on the Predator, and I think 'lan1' on the Vero.
Once you're at the u-boot prompt (customize the ips as appropriate for your network, I run my tftp server [dnsmasq] on my main openwrt router):
setenv ipaddr 192.168.1.95 (unused ip)
setenv netmask 255.255.255.0
setenv gatewayip 192.168.1.1 (default gateway)
setenv serverip 192.168.1.1 (tftp server)
fdt addr $(fdtcontroladdr)
fdt rm /signature
tftpboot $(loadaddr) predator.bin
bootm
https://firmware-selector.openwrt.org/?version=SNAPSHOT&target=mediatek%2Ffilogic&id=acer_predator-w6
kernel ie. https://downloads.openwrt.org/snapshots/targets/mediatek/filogic/openwrt-mediatek-filogic-acer_predator-w6-initramfs-kernel.bin saved to tftp server as predator.bin
(or use 23.05.4 version, I've yet to use the snapshot version actually)
You should get openwrt booting up.
From root shell
ip -4 addr del 192.168.1.1/24 dev br-lan
ip -4 addr add 192.168.1.95/24 dev br-lan
ip -4 route add default via 192.168.1.1
echo 'nameserver 192.168.1.1' > /tmp/resolv.conf
at this point if all goes well 'ping 1.1.1.1' and 'ping ipv4.google.com' should work.
get date +%s output on another linux machine. call:
date -s @the_date_as_an_integer
this should make https work (certs need a close to valid date).
you might also be able to just:
date -s @$(wget -q -O - http://app.elentari.org/time_unix)
Now from another machine you should be able to:
cat ~/.ssh/id_*pub
copy one of the keys into /etc/dropbear/authorized_keys
this should make:
ssh root@192.168.1.95 id
work without a password prompt
ssh root@192.168.1.95 md5sum /dev/mmcblk0* > md5sum.txt
ssh root@192.168.1.95 'cd /dev && echo mmcblk0*' > mmcblks
for i in $(cat mmcblks); do ssh root@192.168.1.95 cat /dev/$i > $i; done
md5sum -c md5sum.txt
All the above needs testing
if the checksums pass, gzip -9 the files - they'll shrink a lot.