Recover Lumix S5ii Footage

I’m facing a single-file disaster with my Lumix S5 II: the camera’s in-body rescue routine only spat out a 23 GB *.mdt file instead of the original 4 K 50 p H.264/AAC *.mp4. The card itself is perfectly readable on my computer, yet every player and editor refuses to open this MDT container... (Budget: $10 - $30 USD, Jobs: Audio Editing, Audio Services, Data Recovery, Digital Forensics, Video Editing, Video Processing, Video Production, Video Services)