You can buy adaptor leads to do this if you dont want to cut the cars wiring, this is also a problem with vauxhalls (where I seen it before).
The wires are swapped round. It's the strangest thing, the radio will switch itself on, for approximately 3 minutes, before switching off again, either when the central locking is used or a door is opened.
It's wired upto the eco live feed. It's needs a permanent live.
There's one on the connector block, but on the new head unit, it's probably going to a blank connector. I had to find the live and swap it but pulling it out of the connector and putting it where the yellow radio live feed needs to be.
Once I turn the key the radio comes back on and stays on, but when the key is turned off and removed the radio stays on for a few minutes. I can hear a relay click when the radio shuts off. The memory works fine. I thought it was the radio ( bought from Aldi) but it doesn't do this in any other vehicle.
No, it's wired to the eco live which stays live for a minute after switch off and kicks back in when you open the doors. Nothing to do with the head unit, it's not correctly wired.
You need to change that for the perm live feed. Mine did exactly the same until I sorted it.