Battery / BMS problems on A2B Alva and Speed battery

This is my first post here so excuse me if this is answered elsewhere or is in the wrong place.

I am trying to diagnose a problem with one of my A2B Alva+ batteries. It is not working on the bike. The pins on the battery are reading zero. On my other battery I have a full 40v on the battery output.

I took the "bad" battery apart (Carefully!) and I can see each set of batteries is around 4.10v, so it is totally full. On the battery contacts on the battery management system board I am seeing zero volts out. Both fuses on the board measure ok.

Does anyone have any hints on diagnosing or fixing this?

Thanks!

Is that something burnt in the middle of the 2nd photo down?

Is this the same battery as on the metro?
Looks similar... Might be hard to source a new bms if it's dead. Anyway did you check the voltage at the connection ends of the sensing wires? One of the wires might be faulty, pull the connectors off and inspect for corrosion etc. Also check the on/off switch and wire for same. I assume you've plugged it into a charger briefly.
Something has turned the bms off ( or its toast)
That's the simple stuff done.

I dont think this generation of A2B rear battery has a manual On/Off switch ?.....confirm ?
Does the Alva have the "electronic key" on the bike ?
If so i suspect there may be a electronic switch on the BMS board to isolate the battery ...and that is activated remotely from the bike via the 2 small control wires (blue+ green). seen beside the main power wires inside the front end cap.
Just a guess but maybe you have to "activate" the power pins via that circuit ?
I have a similar pack, so i will look for clues !

Thanks all!
Indeed the Alva+ doesn't have a hard switch. It has a key fob type thing that turns the bike on. The one pack I have that is working reads 36+ volts out the pins all the time and the bike works fine. The other pack reads zero and the bike does not work. The good pack works in both bikes. I will re-verify this tomorrow.

I also though the two small wires might be to turn on the battery but I was afraid to blindly short them to see what happens.

Here is the full size pic of the bms. I don't see anything obviously burnt:
https://www.dropbox.com/s/ejt8p49vrjtwojg/2016-06-12 15.55.28.jpg?dl=0

Hi, sorry to comment on an “older” tread but I am having this exact same issue and kinda stuck at this point.

Measuring 41.5 volts with my meter at the yellow connector that plugs to the bike but nothing happens when I do plug in the battery in.

Did you ever find out what the issue was?

My battery is on the A2B metro and it has an on/off button that lights up blue when I turn it on and measure the 41.5V

Tks in advance for any info....