I have one of these. The speaker grounds must come back to the radio. Our old original radios allowed the speaker grounds to be grounded to the car. Also, recheck the wiring to the fuse block. There's one power wire (red wire) that connects to the radio connection on the fuse block. This wire has an internal fuse built into the wire. Check the fuse and make sure it's not blown. The green wire goes to a switched connection on the fuse block that gets power when you turn on your lights. The orange wire is for power to accessories like antennas, mp3 players or cd players. If you don't have any of these, it doesn't need to be hooked up. Also, carefully read the operating instructions. This radio has some unique ways to tune but they do work. Lastly, I really like the sound this radio produces. If you can get past the simple but different way to tune the radio and get it to produce sound, I do not believe you will be disappointed. And, the best thing, it does look original in the dash.
Thanks for the information, it inspired me to go and have another look and armed with some more information from the supplier I figured it out
I feel a bit stupid but it looks like the issue is solved.
The new radio looks like the original radio when viewed from the front and the balance knob is a dual function knob on the new radio. (balance and fader)
Well it turns out that the balance knob was getting stuck and not allowing full range so I was not able to get the correct function to get front or back speakers working.
I didn't want to force the knob but it took a bit of extra force to get the full range and now it is moving free.
Anyway, it looks like its all sorted now.
Here's a few pic's comparing the original radio with the new radio.
Original radio (front view) is AM only
New radio (front view), note this is AM and FM
Comparison of new and original radios (side view)