My oral b 6000 electric brush is working but lights are not working

i came across the situation in my oral b 6000 handle type 3765 it is working fine it has Bluetooth connectivity and 6 mode operation. it is turning on and off even gets connected to my paired phone and shows operation mode but the lights (LED) handle ring, mode light even battery light is not working can any one help me with that ?

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Can you open the toothbrush? The article at https://www.ifixit.com/News/43726/a-tear... may help.

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