Unihertz Jelly 2 flashing stock ROM - DA ERROR

For kicks I tried a GSI ROM on my Jelly 2. It worked well except GSI ROMs don't seem to work well with VZW. So I'm looking to revert to the stock ROM. I have gone through the guide they posted here https://drive.google.com/file/d/1qVlaYucvE44ZJqF1RCHGknEBQWy_Z65m/view and I have the drivers installed and the phone is recognized as "MediaTek PreLoader USB VCOM (Android) (COMx)". Using their flash tool linked from the doc, the tool recognizes the phone on COMx (x depends on which USB port the cable is plugged into) and when I click "Start All" in the tool, in about 3-5 seconds the progress bar fills red to 100% and says "DA" in front of it. Then at about 125s, "DA" changes to "DA ERROR" and that's the end of the process.