ezt3d - Upgraded Controller MKS Gen_L

So out of curiosity I bought the cheapest printer in ebay - here in Australia. IT's an ezt3d delta kossel. I won't bore you with the details, there are many shortcomings. But it does print exceptionally well for a delta! IT's just getting it to print that's a pain. The shipped controller board is a custom ezt3d STM32 controller, rather nice hardware specs, but the most awful firmware ever. And no usb port to upgrade!. Who builds a firmware that can't read more than 8 char of a filename, I