Help – Euphorbia Acrurensis

Is this a fungal infection?

I recently brought home a new Euphorbia, and I likely have stressed it out during the transition. I repotted it a few days after bringing it home, but the top of the plant was slightly damaged during transit. Unfortunately, the damage has gotten worse over the past 2-3 days. So far, I’ve blotted the damaged area with a hydrogen peroxide solution and have avoided watering it, except for watering sometime after bringing it home. I’m concerned about what to do next. Add kelp to the soil, antifungal treatment, or possibly cut off the damaged top?

Any advice would be greatly appreciated as I love this plant, and it was pricey. I plan to reach out to the plant shop tomorrow as well. Thank you!