will not turn on when plugged in

Hi,

Have you tried inserting batteries into the radio to see if it turns on in case there is a problem with the power cord or the AC power supply section of the motherboard?

If it doesn’t work with batteries either then the radio will have to be opened and the problem of no power further investigated.

Without a schematic diagram it will be difficult, but you may be lucky if you start doing some static testing (i.e. no power connected) from the power input to the radio inwards using an Ohmmeter and also looking for any obvious problems such as blown capacitors, burnt out components etc.

Here’s a link to the ifixit SONY ZS-BTG900 guide which may be of some help in gaining access to the internal components.