No sound from the speakers

[Bean]

I finally replaced the dash speakers with CRB-120PP 2-Way Coaxial Car Chassis Speakers 60W Max 4 Ohm on my e280 estate as the old ones, Kenwood, were blown. I have left the back speakers, old pioneer, as I like the ‘retro’ look. The head unit is a Becker Mexico radio/cassette. After some alterations to the CRB-120 clips, I was finally able to install them. I turned on the radio and there was no sound from any of the speakers. I took out the headunit and tested each speaker with a AA battery. Instead of a ‘popping’ it was more of a static noise. Is that normal? Any suggestions would be most welcome. Could it be the ISO speaker plug adaptor? I would like to solve the problem as the only car audio shop near me is Halfords.

 

[Bean]

I've re-wired the ISO harness for both the radio and the speakers. The speakers work for less than 2 minutes and then there is a huge amount of static. I presume this is either a grounding issue or the head unit. If it's grounding, I'm not sure where to start.... Any suggestions much appreciated.