This gets tricky! You could have a bad battery, the induction coil is bad or the S2 SoC logic is damaged.
I would get a USB power meter to put in series with the charging puck so you can see what is happening when you place the watch on the puck (start off with the puck alone) take note of the steady state of current draw. If it doesn't change it's likely the puck or the watches induction coils are not working. Try a second puck if that still fails then it's likely the watches induction coil or the battery is bad.