Alysria

I have a 1990 Subaru Loyale. Here recently I've been having issues when starting the vehicle. When I turn the key it gives a click, and then all power/electric is gone. I have to pop the hood and remove/replace the negative battery connector from the battery and try again. When this first occurred it was intermittent, but now seems to happen every single time I try to start the vehicle and it has become extremely frustrating, especially when I'm back and forth 5-10 times between under the hood and trying to start it again. I've just recently replaced the battery and alternator, but neither helped or fixed the problem. Any ideas would be appreciated.