Any advice on how to clean this? Purchased bag here and this is how it was sent to me.

As title states, I purchased a bag from someone on here and this is how it arrived. Im so upset. There a substance all over the interior and it also has chewed gum stuck in wrappers and other misc garbage.

I contacted the seller and the only response i got was " it's just dry shampoo". This was not so closed in listing or private message fyi. I'm not sure I want to blast the seller but I do want to try to salvage this. Granted it was not expensive, but it's the point.

Who knows if it is but it's all over an I can't put anything in the bag. I cant wash it because it's leather. Allegedly.

How should I try to clean the interior?