Swallow EQ No Battery Error

[bobloblaw]

I have recently started to experience some weird behaviour with my Swallow AC/DC EQ.
It all started when I connected two 3S LiPo's in series to charge and accidentally plugged the balancer plugs around the wrong way.
Obviously this resulted in some rather large sparks and the need to change my pants…
After this, one of the LiPo's refused to charge and the Swallow errored out with 'No Battery'. At the time I thought that it was strange as the balance taps all showed voltage for all cells, my multi-meter read an expected voltage for 3S and when hooked up to a heli, all servos worked and the motor would spin up as normal.

Last week I received a couple of Turnigy 6S packs for my Protos. The first thing I did was cut off the bullet connectors on the Turningy's and solder on Deans to match my ESC. All went well and both batteries successfully powered on the Protos and she spun up as expected.
I decided to charge the batteries to get ready for some flying. The first one took 6 hours - seems the cell balance was waaay out.
This morning I hooked up the second battery but when charing the Swallow says "No Battery".
On the balance screen, all six cells show voltage (~3.8V each) and when connected to my Protos everything works as expected.
I am pulling my hair out here. Have I damaged something when soldering the Deans?
Any ideas would be appreciated.