u/Kirks-Creaming-Soda

My brother has been completely neglecting and has abandoned his snake so Im taking over care of her but Ive got no idea where to start!

I completely cleaned everything as nothing had ever been cleaned and got her new bedding.

Im a little worried as the heat pad isnt actually heating up through the bottom much and if she may need a new cage, whether it be for her size or a better set up with a heat lamp.

She's at least 3 maybe even 4, he was feeding her 1 adult mice every week or maybe 2 weeks Im unsure, is this the right amount of food? How should I proceed in upping her food amount if I have to at all?

Any and all help would be greatly appreciated!