Picar -x Hat v4 failure

I have just reached the stage of zeroing the servos which went smoothly enough. However I noticed a smell emanating from the Hat but discounted the possibility of an issue on the grounds that it was just new components giving off an odour. When I had mounted the servos on the chassis I noticed that the lights on the Hat had gone out and thereafter I was unable to turn the Hat on again. It is dead so far as I can tell and the smell was clearly the symptom of a more serious issue.
How do I apply for a replacement?
Update: for some reason I turned the Pi/Hat on 24 hrs later and the Hat’s green lights came on (no red though) but unfortunately they turned off 5 minutes later. I think I can safely say the Hat is kaput.

Thanks for the details.
A replacement robot hat will be sent to you.
Once you receive it, please follow these steps to get reinstallation:

cd ~/picar-x
sudo bash i2samp.sh

After the successful installation, please start your Raspberry Pi and proceed to run the examples.