Try checking...
If there's a switch to change from turntable (phono) to your phone input jack.
When you plug in your phone, does that automatically switch out your turntable? If so, the phone jack itself may be jammed (stuck) internally in the aux mode and not releasing when you remove the plug. That just happened with my daughters phone that got stuck in headphones mode.
Are the wires to your cartridge disconnected?
It could be an internal wiring problem, so in the arm or in the box. The faint sound you hear is just the stylus (needle) in the groove playing music. That's normal.
Kenny
If there's a switch to change from turntable (phono) to your phone input jack.
When you plug in your phone, does that automatically switch out your turntable? If so, the phone jack itself may be jammed (stuck) internally in the aux mode and not releasing when you remove the plug. That just happened with my daughters phone that got stuck in headphones mode.
Are the wires to your cartridge disconnected?
It could be an internal wiring problem, so in the arm or in the box. The faint sound you hear is just the stylus (needle) in the groove playing music. That's normal.
Kenny