4 month old puppy bites and tears up his place bed out of frustration.

I’m encountering a problem where my 4 month old GSD puppy is biting and tearing up his place bed out of frustration when we’re training. We’ll work on a command and he’ll do it well a few times and then he’ll just decide he wants to go bite his bed or try to nip my hand. When he bites we just say “no”, ignore him, and once he’s settled we either try to command again or start out with an easy one like sit. The hard part is when he run to the pad that we use for place and starts trying to rip it up. He always goes to the pad and never rips up anything else. I’d like to train around this instead of just picking up “place” every time we do some training in the house. It usually takes me physically removing him by the collar or the leash before he snaps out of it and wants to train again. I’d cut the training sessions down, but he’s still focused and wants to do things. Maybe we need to take 3-4 minute breaks and do multiple sessions? Anyone dealt with puppy frustration like this?