Hi, i have a MK2 golf 1.6 driver 1990.

tried to start my car and i heard a small pop, as if it was coming from the fuse box. now when ever it turn the ignition the battery cuts out (or so i assume as my digital clock on the dash resets to 00:00 each time) the engine doesn't turn over what-so-ever also when i put my foot on the break or turn the head lights on, the battery also cuts out. When i turn the heater or hazards on there is a ticking coming from the fuse box. any ideas what has happened and what i need to do to fix it? i took the battery to halfords and they said it was fine, also put a circuit tester one the battery, it lights up on the RED wire but as soon as i turn the lights on (which don't come on) the tester is not lighting up. any help?

Ed