Hey, guys first time posting in here but I recently bought an HT-700 at a thrift store. But when I took it home and put some batteries in it, it started making really loud droning noise. nothing will make the sound go away even the volume gets louder when I turn it down a softer when I turn it up. The LCD screen flickers when it gets loud and gest faster but that's about it. maybe there's a bad connection somewhere but anyone has any ideas?