New starter, battery and alternator

I own a 2003 Jetta GLS 2.0L The car will run for 30 mins at most and loose power in the radio first than ac/heat and finally the car will shut off and not crank and start it clicks and the dash lights flash when attempting to start it up.

Could this be wiring issue, or an blown fuse or maybe relay? Have checked the voltage of battery and alt. Battery was/is having voltage regulation issue even know it’s brand new. I heard there can be issues with the positive wire that connects to the alternator and battery or the alternator to starter?

I was having a water leak problem coming in from under the dash, i sealed off the ecu wiring box. I’m wondering if maybe there’s a blown relay or fuse under the dash?

sounds like alternator is not charging your battery. Cars running off the battery until it's dead.
If it's a reman alternator. Been know to be bad out of the box. Check all your wiring on what was replaced.