water in trunk/DSP problem

[Gurjit]

sunroof drain flap was stuck closed = lots of water in trunk

i didn't notice anything until i turned my speakers off by pressing the left volume button in.

then when i went to turn the sound system back on i got nothing
so i poped the trunk to check fuses and found water in trunk over the fuses on R side, and over cd changer on L side

fuses for audio all good

the left button doesn't turn the system on anymore
gps works fine = no sound

when i press menu the DSP options don't come up and when i go to settings it has 4'1/2 written on the top right

how do i isolate my dsp amp as the problem??? so i can get around to finding a replacement and fixing this issue