Twizy STOP and Batt lights are on

Hi Everyone,

I am in a bit of a pickle that perhaps you can help me with. The STOP/batt lights turn on and off on every ride now. My local dealership has no clue what to do. And an I really need it fixed to clear an upcoming car inspection.

I own a Twizy80 that I tuned with an OVMS v2 module about 6 years ago and then removed the OVMS/never fully installed it.
Everything has been running smoothly until about a 8 months ago when the STOP+Batt lamp turned on accompanied by some beeps. I got a little scared, but drove home and, since it turned off again before I was home, I really didn't think too much of it. A month or two went by and it happened again. This continued for a while, some trips nothing, some trips had lights and beeps. Sometimes it was on for seconds - sometimes a minute or two. I searched around for a solution, but never really found anything - and I just hoped it would stop by itself :) Then one day the car turned off in the middle of an intersection, eventhough the main battery had plenty of juice. From what I read online it could be the 12v battery so I exchanged it for a new one. But the issue kept happening and now the serv light was also on (for a while). I thought the new 12v batt was defect and got it tested, but it was perfect. I then took the Twizy to my local Renault dealership and asked if they could troubleshoot it and also do a check on the main battery (that I rent). It was the first time they had ever seen a Twizy up close (we live in the same city so they had seen me darting around). After a few days a guy called and said the main battery was 99% and that they had no idea why the lights kept turning on and off - they could not talk to it and had tried al sorts of cables and shit.
I didn't know what to do but I figured it might be the 12v charger (don't even know if the twizy has one of those...) but I started to charge the 12v battery when I charge the main battery. This resulted in the car not suddenly turning off anymore, but the beeps and the STOP/Batt light still turn on and off a couple of times on every ride.
I am a little perplexed on what to do now - and I have a vehicle inspection coming up. I doubt it will pass a vehicle inspection with a big red stop light and beeping...

What should I do? What can I do?

Also: Why can't the dealer "talk" to the car?
Is it because I tuned it? Can I revert that and take it back to them? Or should I give up on them and that? :)
Isn't it wierd that the main batt is in such a good condition after almost 8+ years?

I have reconnected the OVMS and thought I could get some info out of that - but I am quite a noob, but I did these:
VERSION
OVMS Firmware version: 2.8.6/RT3.7.2/V2/RTP8

BATT
Volts: SD:5mV ?C7:+10mV ?C9:-10mV ?C12:-10mV Temps: SD:1C OK (@11:00 today)
Volts: SD:5mV ?C1:+10mV ?C3:+10mV ?C5:+10mV ?C7:+10mV ?C8:-10mV ?C9:-10mV ?C10:-10mV ?C11:-10mV ?C12:-10mV ?C14:-10mV Temps: SD:1C OK (@20:00 today)

BATT V
P:57.70V ?1:4.125V 2:4.120V ?3:4.125V 4:4.120V 5:4.120V 6:4.120V ?7:4.125V 8:4.115V ?9:4.110V ?10:4.115V 11:4.115V ?12:4.110V 13:4.120V 14:4.115V (@11:00 today)
P:57.90V ?1:4.135V 2:4.135V ?3:4.135V 4:4.135V ?5:4.135V 6:4.135V ?7:4.140V ?8:4.125V ?9:4.125V ?10:4.125V ?11:4.125V ?12:4.125V 13:4.130V ?14:4.125V (@20:00 today)

BATT VD
SD:5mV ?1:+10mV 2:+5mV ?3:+10mV 4:+5mV ?5:+10mV 6:+5mV ?7:+10mV ?8:-10mV ?9:-10mV ?10:-10mV ?11:-10mV ?12:-10mV 13:-5mV ?14:-10mV (@11:00 today)
SD:5mV ?1:+10mV 2:+5mV ?3:+10mV 4:+5mV 5:+5mV 6:+5mV ?7:+10mV 8:-5mV ?9:-10mV ?10:-10mV ?11:-10mV ?12:-10mV 13:+5mV 14:-5mV (@20:00 today)