Airpods 3rd don't appear as a device and only blinking white

I recently had problems with the left side of my airpods. It just wouldn't connect or show up.

I did the forget device process, connected it again and still the left side didn't work.

I reset the case by holding it down for 15 seconds, and after that my airpods no longer appears as a bluetooth device, nor does the popup appear on the iPhone.

I've done all sorts of procedures, and now when I hold it for 15 seconds the red light flashes 3 times, then flashes white 2 times, and then flashes red again for a few seconds.

I left the case plugged in for 1 hour and when I open the cover the light turns green but flashes white again. If I take the airpods out of the case, it stops flashing and if I put it back in, it flashes white again.

I don't know what else to do.