[cypher]

What were you doing when he bit you? Was it in or out of the cage?
Sometines they don't like to have hands in the cage, especially when the cage is very small they feel their territory is being invaded which can be threatening for them, with a small bin cage it can be difficult not to approach from above & being prey animals this is quite frightening for them.
I would suggest taking him out to a safe play area for any interaction & try to cange food & water when he's sleeping, fresh water daily.
What sand do you have? It's very. unusual for a Russian not to love sand.
How often do you clean the cage? Over cleaning stresses them & that could lead to biting. Spot clean pee as needed then just do partial cleans, maybe half the cage every few weeks or so leaving the nest & hoard alone as much as pooible.