Found this on another Forum, and I've added a few other codes you can use to check stuff out on the Z500 :-
* Battery information: *#0228#
* Firmware Version: *#1234#
* FTA Hardware Version: *#2222#
* FTA Software Version: *#1111#
* IMEI (serial number): *#06#
* Integrity information (?): *#1235789#
* Locking status: *#7465625#
* MP3 test: *#0673#
* Test mode 1: *#9999*0#
* Test Mode 2: *#9998*324# and *#123580#