My AirPods Pro 1 developed this problem too. It's clearly a logic problem (software or hardware?) as they blast white noise, either to check your ear (like the fit test), or for some other feedback issue, and then it just never turns off. Mine work fine in normal mode, but transparent and noise-cancelling mode they are useless.
I took them to an Apple Store here in Japan, and they just said the only fix was to buy a new pair.
I "fixed" the problem by getting a pair of third-party ANC headphones for one-third the price.
- The third-party headphones are larger, but they are much easier to put on and take off than the AirPods are to put in and take out.
- They don't fall off like AirPods will fall out at times.
- The batteries last much, MUCH longer.
- It is slightly more onerous to change devices, but at least they work.
This kind of poor customer support, and Tim Cook's appeasement of our tantrum-thrower-in-chief has made me stretch out the life of every Apple device as long as I can. I have numerous Apple devices, but I am certainly not a loyal customer. Tim Cook's number-driven greed precludes any loyalty on my part.