It looks like an argentine rainbow boa.. doesn't look like a brazilian at all really.

I've seen rainbows dig in the substrate before.. it's normal.

These guys need HIGH humidity. 70-80%.. mist a couple times a day. NO screen lids.. in fact I wouldn't use a tank at all, but a tub with only a few ventilation holes drilled in it.

Don't let the temps go over 85 degrees.. the heat can kill them.