Stereo power issue

[Stu604]

i have been having this issue for some time now here is what's happening
First of all my battery keeps going dead when we don't use it for a day or two which leads me to drain
So I tested for the batt drain. Under the hood stereo fuse read high for the voltage drop.
The stereo the stereo flickers on and off intermittently and then after a shot time just stays off.
Hooked up a after market double din touch screen and it fried the touch screen
Also the head lights dim in and out
Any suggestions

 

[Stu604]

And when the stereo cuts out the 12v and the ign wires stay lit up when a test light is put on them