White noise/ feedback from radio

[Gjm-Mx5]

1. My model of MX-5 is: n
2. I’m based near: __
3. I’m looking for technical help or recommendations on: _
   Just found N/s footwell wet and mouldy, not been in car for about 3 weeks. I’m guessing this will be the drains under scuttle panel from reading through the forum.
   No water damage visible in fusebox but some horrendous white noise/ feedback coming through all speakers even if radio is off ?
   Any ideas on where to start?
   Nc 3 hardtop!
   Thanks in advance
   
   

[CBRDEANO]

I would take out that fuse box cover panel ( not just the access door ) and look at the full fuse box.

There is a lot more behind that panel than the fuses you see through the door.