Main drain should be air locked.
The pump hose may or may not have been frozen. When I lay one after I close a pool, I set it to go down hill. Once the pump starts, it creates a siphon. When the water is gone, the siphoning usually drains most of the water out. There is no check valve to trap air/water in the line on your Rule pump.
If you decide to remove some of the snow/ice from the cover, be sure to only use a smooth plastic shovel.
Do NOT detach the anchors from a weighted down cover. If there was too much weight, the straps would slide 1st to ease the tension.
I have had customers put them over an empty pool. After the strap slid some, it was about 50-50 as to whether it would slide and release or the spring would warp and let go. Very fixable. The cover was fine after the repairs, It didn't need shipping out either.
Lets see what a little faith does.
Scott