Figured i'd give an update, in case anyone came across the same issue, as it seems to be resolved.
The fault appeared to be a dead BMS.
Zero and the dealer ripped the bike apart for several months. They replaced the controller and main harness (the big taped up fucker with a contactor in it), which removed some symptoms but not the problem. They then replaced the BMS system, and i finally have my bike back in working order.
To zero's credit, they did all the work under warrantee, and the shop that did it, busted their ass to find the issue- so if either of them see this post, you've got nothing but positive vibes coming from me.
AS i look back, i believe the problem was manifesting small issues long before the outright failure, but i couldnt isolate the issue. So long run, i believe the BMS was likely bad from the near start, but managed to run until it finally crapped out altogether.
Issues prior to failure:
-Bike notifications worked initially (finish charging, etc..) then after maybe a year, just suddenly stopped one day. Connecting remotely would show location and battery status, although frequently would not reflect plugged/unplugged.
-Throttle faults, cleared and recurred. Unknown if they will come back. No issues found during service.
-Dc/Dc low voltage fault, again, cleared readily. only happened twice, about a month or so before the failure.
-One time it reported that the bike had fallen over, when i know for a fact it had not. It hadnt recorded the event in the bike logs either, just sent me a notification to stir anxiety i assume.
Issues AT failure:
-Bike suddenly stopped, as if in a SERIOUS state of regen. To the point of being near impossible to push, even with key off. The motor causes a physical drag as if the leads are dead shorted (which considering the failure, they MAY be)
-Numerous critical faults. Battery not registered, invalid battery, basically a handful of serious random faults.
-Bike will turn on, reflect the pack voltage properly despite the faults, which will not clear, and the bike will not enter a ready state.
-Bike still impossible to push in keyed on state.
-Plugging in a charger cable will result in no response, the bike would not wake to charge or acknowledge the plug.
-Connecting remotely would still show the battery status and bike info.
So they gave it back, and after a very awkward moment of "how the fuck do i ride this thing again.." it runs like a champ.
Bit of a shudder at low speed which it didnt have before, like a heavy vibration while accelerating around 20-60kph or so- it goes away as i speed up. Makes me think there's maybe a phase or calibration issue to be tweaked. anyone heard of that before?