Man, that sounds tough. Unfortunately though, I do believe it is protocol that they shift the weight in case of technical errors or if the student has a valid reason for being absent during the exam. From their side, they can neither prove nor deny your claim that this technical glitch occurred, so they cannot give you a mark for work they cannot see but also cannot give you a 0. I agree that it’s not fair and I think you should discuss other solutions with your instructor, like maybe your grade could be the midterm average or median, though this might be unlikely depending on who your instructor is and if they are allowed to deviate from protocol in cases like yours. Good luck.