can anyone tell me what causes the green light of death
this is what ive heard it called ie tomtom shows green light and nothing else

Hardware failure.
Can be the GPS chip, memory, CPU, sometimes even a burnt diode for the charging circiut.

thanyou just that ive seen so many of these on ebay and was just wondering if this is a common fault that can be easly fixed

You'll never know if it is just a damaged charging circuit or something really bad.
And withouth professionla soldering tools and testing equipment it will be impossible to fix even minor problems.
If you need the device for spares like a screen, ok, otherwise stay away from these devices.

thankyou downunder

You're welcome!