I have a TB47 battery that after upgraded by firmware v.1.7.0.90 goes into error state at end of full charge. LED # 3 (if counting from bottom) blinks twice and when I look at battery in DJI app it shows 100% charge but cell voltages are not alligned.

I fully discharged the battery once to see if it would help rebalancing the battery but get the same blinking at end of charge. Has anyone had this before? Is it fixable or do I contact DJI with a warranty claim?

Sorry man, this one sounds like  you will need to contact DJI for warranty replacement. You have already tried the deep cycle to reset the battery down to about 7%.... Shouldn't take a chance with this one....

Rich