Ah yeah! a 3... Yeah man they are tough little suckers. Hard to brick.
I should know I beat the living pulp out of mine in it's lifetime and it's soldiered on regardless. Honestly think that with just a bit more setup you will have this rolling.
STEP 1) Ditch dropbear. Get yourself some ssh keys and once you have logged in with them successfully once.. Switch that FALSE to TRUE that we looked at in /usbnet/etc/config...
make the key, keep the private in ~/.ssh/
(this is the default from running ssh-keygen and just pressing enter about 8 times lol)
get the public key and shove it in /usbnet/etc/authorized_keys (make the file, fill if with the PUBLIC key string)
try authenticating (should "just work")
Ditch the dropbear. That will be a
step forward at the very least
There has to be AT LEAST 5 or 6 guides on here about this more fulsome in detail than my potted guide here.
But I covered the essentials.