Radio volume

Good Evening Just joined the Landry zone I have a 2003 l322 hse After leaving the vehicle parked up for some time. I had no volume on the radio. Up to know I have changed the amp in the boot. This gave me volume for approximately 30 seconds. Then no sound. Switch. The radio of and back on I get sound for approximately 30 seconds I have tried 3 amp which are good. But same symptoms. To day I have replaced the radio head Symptom exactly the same Can any one help me out with this problem please

Hello and welcome
Best to ask over in the range rover section of the forum https://www.landyzone.co.uk/forum/range-rover.10/