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broken neck, You can bleed at the master cylinder similar to the way you bleed at the caliper. No special parts needed.
Loosen the banjo bolt, squeeze lever, tighten banjo bolt, release lever. Just make sure to have towels ready at the banjo bolt because there's no nice way to catch the brake fluid and it will be messy.
If it's still spongy even after all that, ziptie the brake lever down overnight. It helps some people.