OK Stephen. The click you heard is the solenoid and this suggests either a flat battery with only enough power to activate the solenoid or a duff starter motor / bad connection. That the car now works with a fresh battery suggests that it was a simple flat battery.
A flat battery can be one of three things. No 1 is a duff battery. No 2 is a good battery not being charged by the alternator. No 3 is a steady discharge whilst parked and turned off.. You can get a very good idea of which with a simple digi voltmeter. The alternator should charge the battery at somewhere round 14.5v so step 1 is to start the engine, get someone to rev at say 2000rpm and check the volts at the battery terminal. If the volts are 12.8 or even less then alternator problem. If 14.5 or thereabouts then alternator likely is OK. Lets assume the alternator is OK then stop the engine and turn on the headlights for 20 sec or so to burn off any excess charge on the plates. Let the battery sit for 5 mins and measure the voltage. Take a not - likely its something like 12.8v. Let the car sit for half a day and again measure the volts. In an ideal world it wont have dropped even as much as 0.1v showing nothing draining the battery. But if it has dropped then go straight to that windscreen heater button. It should not show any light at all when the car is parked up and the light it does show indicates its using up your amps.
The whine is likely to be irrelevant - after all it can only be there when the engine is running since stationary there is nothing to generate the AC voltage you are hearing. It could possibly be an indication of a duff alternator but see above.
Last comment. Take the car to an auto electrician and not your usual garage. The average mechanic knows sod all about electric circuits and their testing.
Last edited by howard; 11/07/16 06:58 AM.
