May a student continue a discontinued checkride if the CFI who endorsed them voids that endorsement? The Situation
CFI Charlie endorses Student Sara's logbook for a checkride. Sara begins the checkride but discontinues, and receives a letter of discontinuance. So far so good.
Before Sara can reschedule the rest of the checkride, she and Charlie have a disagreement. Charlie has access to Sara's logbook and voids his endorsement by crosshatching the entire text of the endorsement before giving it back to her.
The questions

Is Charlie's endorsement actually considered void?

Sara has the letter of discontinuance in hand. Can she reschedule and complete the checkride without getting a new endorsement?
The test was discontinued. No reason the DPE would be looking in her logbook as a discontinuance is simply a pause in the testing process. She was eligible to test, she remains eligible to test. If she already told the DPE about this the smart DPE would make a note in her test records explaining what occurred. Once endorsed the applicant is endorsed. If the CFI wants to "revoke" her endorsement I believe it's too late.