The controller worked fine until I started Steam. It showed the firmware update popup, I did as instructed, the puck was updated fine, but the controller failed. Now the LED flashes red when I turn it on, it doesn’t react to button inputs, doesn’t connect wirelessly, isn’t recognised as a controller when connected through USB, and shows up only as “Valve Software Steam Controller Bootloader”.

I think it’s reasonable to assume that the firmware is cooked. Naturally I’m opening a support ticket with Valve, but I’m wondering if anyone has any idea on how to resolve it without waiting, potentially for months, for a replacement.