First: ;un doesn't have *anything* to do with the base JB/bridge, so it won't really help you suss out anything meaningful. It breaking after a FW update is *completely* normal (assuming you actually had it working in the first place by having installed USBNetwork).
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If you can't run ;log mrpi nor ;log runme, you are indeed SOL.
I mean, you could try an emergency.sh, but that's usually contingent on the same stuff that ensures ;log works, so, if one's gone, it would follow that the other would be too.
c.f.,
https://www.mobileread.com/forums/sh...63#post3961863
(Also, modifications to that last approach should only be attempted by a trained professional, as a screwup in a bridge emergency script *will* soft brick your device. People *have* killed their device this way in the past.)
(This is bundled in the "K5 JailBreak" package in my snapshots).