So I haven't used my Mavic in a while and knew there would be an update.
I have 3 batteries, so charged them all along with the controller.
Turned on, and started the update to 1.04

First tried failed and the middle 2 battery lights were permanently lit. I cannot turn this battery off now.
Swapped battery out for another one and tried update again, which was sucessful.
Turned off, swapped battery for last one as I knew it would need an update, which it did, update went through ok, battery responds to turning on/off, but shows 'battery error' on controller. Can't start Mavic with it.

So I just have 1 working battery now.
Anyone else had these issues, or know a way of sorting?

Just charge up the not updated batteries again  until they are full and put them in the AC, connect it via usb to the DJI Assistant app  on the PC and then turn on the AC, the batteries should go through and complete the update
When charging don't worry if the lights are static the batteries will still be charging, charge them for a couple of hour each

Thanks for lannes' answer, please refer to it and update the battery on the drone via DJI Assistant 2 again. If the problem persists, I suggest sending the battery back if it is under warranty and we will take care of it for you.

Thanks for your help guys, I contacted support who have been very helpful, but unfortunately we could not resolve the problem so they have to go back  

Credit to DJI,
My batts have been sorted and are on there way back.
Thanks DJI