This new link has the stock firmware for both screen types: HH and original screen.
If you don’t understand what to do - please do some research here first.
Download is by request only - no public link (members only)
Try to confirm which type you have in Settings/About Watch - flashing wrong type will result in upside down screen and possibly no touch response.
You will need SP flash tool - maybe best to use an older version from around 2018.
SP Flash Tool Download All versions for MediaTek Devices
Grab the drivers from there as well.