It seems my filament is burnt when I use PETG
It looks like you have a clogged nozzle/hot end. I use 225°C @ 40mm/s for PETG with 235°C @ 30mm/s for the first layer.

If you print at 245°C, you risk burning the PTFE liner in your hot end. You really need an all-metal hot end to print at such temperatures.

It is possible that you have already damaged the PTFE liner, and this may be the cause of your problem. However, I would check for a clogged nozzle first.