My suburban suddenly would not start - no lights -

My 2000 suburban suddenly would not start - no lights - no radio-no power door locks etc... However, the lights under the side mirrors were blinking slowly and I could hear a "clicking" noise coming from the dash - much like the "burb" was trying to turn something on or off electrically. Do you think this is the battery or an electrical system problem? No previous problem starting.

Check your battery voltage for +12volts off,then have the battery load tested and see if its above 10 volts under load test,if it shows ok,then you may have a high resistance ground in the system that needs to be traced probably at the e.c.m. power because of the clicking it sounds like its going thru the self-test before it starts