Another thing to consider, how was this battery activated for service? It's almost certainly an AGM battery and there are still a surprising number of people INCLUDING SHOPS AND PARTS STAFF who ought to know better, who just squirt the electrolyte in fast and then slap a new battery on a quick charger saying "Come back in an hour and it'll be ready for you". Early in that hour the battery will be ruined. Won't hold a charge.
Any time I buy a battery I insist it be handed over in a sealed box, that has not been meddled with by some bumbling parts man.
You need to allow the electrolyte to drizzle in at its own speed and then charge it for a good 8 hours on a proper low amp smart battery charger or maintainer (not an old stupid one with a '2 - 10 - 50 amp' switch!)
Sounds like this battery might have been cooked.
You're right, that tiny draw shouldn't bother a healthy charged battery. I have left my 800 battery alone all winter 3 times now, no battery maintainer, not removed and stored in a warm garage, nothing, and each time in the spring the SXS spins over like a sewing machine.

The static draw is minimal.