I'm not sure what you mean by "every time I turn it off", or "loud series of beeps"... Are you sure you have an actual Sonicare? Because that doesn't need to be

I'm not sure what you mean by "every time I turn it off", or "loud series of beeps"... Are you sure you have an actual Sonicare? Because that doesn't need to be turned off after brushing (the cycle ends itself), nor is it capable of producing beeps that could be described as anywhere near "loud". In any case, the user manual that helpfully ships with every genuine Sonicare, and is also easily accessible online, succinctly describes the steps to disable the beeping: 1. Put the handle on the plugged-in charger. 2. Press and hold the power on/off button while the handle remains on the charger. 3. Keep the power on/off button pressed until you hear a series of two short beeps (after 4-5 seconds). 4. Release the power on/off button. But, as an actual Sonicare owner: when it beeps for replacement, the head is truly overdue for that. In fact, I synced the replacement schedule of my manual toothbrush (which sees an equivalent duty cycle in my case), and every time I look at both brushes, I have to admit: yup, those need replacement!