Replacement battery for Autel robotics quadcopter controller

My son’s quadcopter controller (Autel Robotics Model # EF5B) no longer takes a charge. Naively thinking I could just open the controller up, get the specs and google for a replacement, I set about to do just that. Fast forward to now: I can’t find this thing anywhere, or any suitable substitute that will fit.

I’m attaching pictures of the controller rear sticker, the battery, and a closeup of the battery data stamp. The battery connector has 5 wires (2 black, 2 red and 1 yellow). The battery needs to fit within an enclosure with dimensions of 98mm long, 43 mm wide and 10mm deep.

I’ve scoured the web, and sent messages to several vendors on alibaba, with no luck so far. Any help would be much appreciated. I’d love to get this off my bench and back in service, as it’s seriously crimping my “dad is a genius” story. Feel free to ask questions or offer advice. I’ve thought about maybe cobbling together an external power bank, but I’m unsure about how to wire the interface, and how to get the correct voltages at each wire. For visuals, see pics below. I have some other video snips I took during the teardown so that I’d have some breadcrumbs to help when I put it all back together. I can take screenshots or post those videos if needed.

Controller rear sticker:

Battery:

Battery data stamp: