T460S Power/battery problem

[braikes]

I recently have been having a lot of power problems with a T460S.

First, after running low on power the other day (and the day after updating the bios which may, or may not, be significant), when I reconnected to the charger, one battery was shown at 9% and charging (but it wasn't) and the other at 0% and suddenly with poor condition (about 1.5% capacity!). I tried various things to get things going again. One thing I tried was re-installing the Lenovo power manager (same version) and that seemed to sort out one of the batteries, which has now charged up to 97% (identified as battery 1 by Lenovo settings, or 2 by Windows 10). However

1. The other battery remains stuck on 0% and although the Windows 10 indicator says 'charging' it isnt.
2. If I disconnect the PSU, the machine dies! It seems to ignore the charged battery.
3. The Windows task bar Icon shows the system as fully charged.

All in all, it's very frustrating, especially as I am travelling a lot for the next couple of weeks which will make on-site support difficult. (I have a contract).

Anybody any ideas?