About Noise, That is normally situation that hearing aid make whistle noise. 4 Ear plug. – If you hear a howling,check the ear (silica gel) is appropriate and whether the size of plug is tight, the appropriate choice of earplugs and plugged, make sure no air leakage.
Looks like charging port broken. Broken unit does not power on. This item is for sale as PARTS.
4 x Ear plug. Input Noise: ≤29±3dB. Sound gain: ≥30±5dB. 1 x Main unit. Frequency Range:450～5000 Hz. 1 x Adapter.