String of tears - brown spots?

[dayzb]

Hello. I recently moved to an environment that gets little to no natural light. To help, I purchased a grow light so my little succulents could continue to thrive. It is around 12" tall with a bulb. The bulb does give off some heat but it is only warm to the touch. I have been leaving the light on for the entirety of the day just to see how the plants would respond (I have very little experience with grow light).
My succulents, my string of tears in particular, have shown lots of new growth. However, now some of them are starting to show brown spots like the ones pictured.

I also added another one of my succulents that is developing some black hole looking things.

Am I giving my little guys too much light? Is the light too hot? Am I not watering my plant enough? Or is it some other pest/deficiency?

Any help would be greatly appreciated!