randomally my v3 stopped reading battery and won't turn on

V3 been used daily for 4 months or so and then mid road trip it failed. Won't turn on and when I plug charger in it says charging mode like . If I press 3 times it says see you . But if I press 5 times it says xmax and does load up but then says battery flay warning .

I left it with no battery installed for 24 hrs and it worked fine for one batterys worth . When I replaced it with full battery it went back to broken mode. Seems like firmware . Iv trydd cleaning contacts multiple batterys etc. No luck. Pulled it apart no visible issue reassembled n still same.

Any idea anyone smarter than me?