Let is sit for a month. It should leak off. Very educational to take one apart once it's dead. Magnetrons are just plain cool looking, 1950s retro, like a prop from Forbidden Planet. Just an empty can with two very strong ring magnets on either end, yet it cooks perfect rice in
25 minutes.There's a HUGE high current low voltage transformer in there feeding the death ray. Don't f*ck with it. It's even more lethal than the magnetron. Makes a nice bookend.
Don't bother putting the oven back together, because it's designed to die whenever a consumer does something amazingly stupid with a source of flesh-roasting em radiation, like opening it up.