My 97 legacy gt won't start and has no power to radio or dash lights but door beeps when opened. I just replaced battery

Sounds like the previous owner may have some information to tell you and possibly refund your money. I bought a car one time from an auction that the trans went out on the way home, come to find out it was full of saw dust.

Look around for a legacy forum specific to your year and ask around there. Maybe you just have a bad ground under the dash somewhere and it'd be an easy fix but it's hard to solve electrical gremlins online, unfortunately.

Sounds like the battery is insufficiently charged, perhaps having been on a shelf for a while. try jumping and driving for an hour at speed. If it doesn't work maybe you bought a bad battery. Look at the simple stuff first....