Too much water can rot the roots. Too little water in a hot climate can cause death by dehydration.

The black streaks are probably stem canker of the botrytis type that entered at pruning cuts. I have seen it spread aggressively when a plant is dormant or semi-dormant, and for that reason I avoid unnecessary pruning in fall or winter. Actively growing plants have an immune response that usually prevents the runaway spread of such infections. If you prune out cankers, sterilize the pruners and cut > one inch below the visible infection and just above a leaf or latent bud (former leaf site). But it is probably not good to keep nipping repeatedly during winter, if you have real winter there.

Yellow canes are dying canes. The fungus might have attacked because the canes were already dying for some reason, or it may have caused them to die. Sometimes roses die back for mysterious reason, for example poor conditions during cold storage before you bought it. No telling whether the plant will survive or not.

Thanks Michael.
Its pretty warm here with temp above 20 Celsius. Night time being 10. We are equal to zone 9 there. This has slightly spread on to other roses as well :(. I have 17 roses planted and don't want them all to get this. Should I remove the plant?

Other plants are budding and this is the worst looking with very few leaves.

Although it might survive and produce new canes from the base, I doubt it will thrive. I would replace it. Possibly the vendor would give you another. It looks like you got a plant with something wrong with it. Most US vendors would replace such a plant.