Sorry to hear about the
led panel. It's decent for smaller kitchen herbs and starting seedlings, but not much more.
I'm in agreement with Gps, you're going to need more room. Also, run a separate circuit for your heater. Anything running 1kW or more should be on its own separate circuit to avoid overloading the others.
metal halide lamps, especially those 400w types using older magnetic ballasts, have a HEAVY initial draw (digital ballasts do not cause this issue as badly but it still exists,) and if the 1500w heater is on that same circuit you're guaranteed to cause yourself issues.
Be wary of LED right now. While I've had great success in both home and commercial setups, most sellers of LED equipment are selling you nonsense, as cable has noted.