The official Via firmware and firmware generated using QMK uses the .bin extension. In the temporary .build folder, there’s a .hex file, but it doesn’t work for flashing.
Could it be that they switched the MCU they used for the PCB because of shortage? Do you have a picture of the MCU on your pcb? I couldn’t find any online for Bacca70
No, sadly I can’t even flash the original firmware on it. It can go into DFU mode, even erase the existing firmware, but errors when reading any firmware for it.
I reached out to him on Geekhack a few months ago and got a response within a day or two. Might be worth a try.
I worked with him to troubleshoot a PCB a few years back, the AT101 replacement board. Got it all sorted out through discord. I can’t find him there now though. I think group buy anger trolls probably forced him to either get off of discord or change his username.
I contacted him via Discord, and he sent me a working firmware file!
It turns out the original PCB was ARM, and then the silicon shortage happened, so they switched to the 32u4 before the group buy. The incorrect existing firmware was merged into QMK and Via, and no one caught the issue until I did. Haha.