Tstat8 bricked

I’m updating my Tstat8 to 9.4 firmware. Nine of ten thermostats upgraded correctly while one go stuck part way during the update. Now the thermostat is flashing (ON short, OFF short, ON short, OFF long ) and nothing is written on the screen while usually “Updating…” is printed) and doesn’t accept firmware upgrade anymore. I’ve tried also disconnecting it from T3 Controller and connecting it directly to USB RS485 key unsuccessfully: ISP tool reports “device is offline, please check the connection”. Connection is ok because I’ve tested several devices with diffenrt modbus ports.
Any idea to restore the thermostat in order to flash the firmware?


The device has been ‘bricked’ as we say in the electronics hardware business. Fortunately its easy to recover the Tstat8. There is a bootloader which is active in the first few seconds after power on, during this time the stat is looking for a connection to the ISPTool for new firmware. You have about ten seconds to try the update after power up.
In my example here I am recovering a device on the subnet of a T3 controller which is also possible. If you’re having troubles over Ethernet you can do a direct RS485 connection as you tried, but this time try again loading firmware again right after power on.

If you’re not sure of the ID you can try at the global broadcast ID of 255 but be sure to do this with only one device connected.

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