Q.Why is my blackberry not growing?
I planted a blackberry that is meant for a balcony last year. We had a lot of growth last year and a few blackberries. However, it has not done anything this year other than showing a bit of growth that could become leaves. These have not done anything noticeable in a couple of weeks. Could the plant be dead or is it possible to still be dormant despite the warm weather? The growth happened before a cold snap where it got below 0C a few nights and I think it might have killed it.

Certified GKH Gardening Expert
This article will help you determine if the plant is still alive or not: https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm