Chris.....hth..
Sometimes "voltage error" can be caused by a faulty plug, not the battery.
I have had this with a faulty balance lead plug... I use extension balance leads from the charger and they can be a bit fragile.
Could be worth checking. I've had that message a number of times and it has always been the leads. I have only had one Lipo failure and that swelled badly while stored..! I now, always storage discharge my Lipos.