There is a post here in the forums for unbricking a device,
Summarizing here:
Cycle power, in the first few seconds after power up the device will be repeatedly blinking the heartbeat or backlight two times quickly, this is the bootloader period where you can load firmware. Use T3000 → Tools → ISPTool to load firmware, you can download firmware manually from here if you don’t already have it on your PC from the earlier efforts.
https://temcocontrols.com/ftp/firmware/