I left food in the microwave as shabbos started. Which is worse ?
1) Leave it there & bal tashchis
2) open the door & the light goes on
3) unplug it & the digital numbers go off
Disclaimer: I am not a Rabbi. All halachic inquiries should be addressed to your LOR.
1. There is no Baal Tashchis concern because by definition BT only applies when ruining usable food for no constructive purpose. (Not violating shabbos would certainly rate as a constructive purpose.)
2. Even if there would be a BT concern, we would have to weigh that against the issur involved. Leaving food to spoil is at worst an issue of a derabanan and would certainly not outweigh chillul shabbos d'oraysa. And even if the chillul shabbos involved here would only be derabanan (possibly the scenario of unplugging it), BT would still not outweigh the chillul shabbos because the CS involves actively doing the issur while the BT involves only passively allowing the food to spoil.
3. As mentioned before, you are out of luck. There is no way for you to remove the food from the microwave.
4. There would be an eitza to have a aino yehudi remove the food as the turning on the light is a pesik reisha and amira l'akum in a case of pesik reisha is allowed.