Starts sometimes, dash lights blip sometimes too

Turned my explorer off one day and 5
minutes later it wouldn't start, tried to
jump it and wouldn't start, charged
battery the next day and it started, ran
for a week and won't start again.
Alternator is good, put new starter on
and new starter relay and didn't start,
tried to jump start it and it started right
up turned it off and started right up
again, next morning wouldn't start and
clicking like dead battery, charged
again won't start. When I turn the key
sometimes the dash lights blip and go
out and won't start. Sounds like a short
somewhere doesn't it? Any help greatly
appreciated