Just replaced the battery today in my 09 G37s. Got to the gym later that day and the car clicks once then the cluster goes black. The radio also is black and won’t turn on

 

What basic troubleshooting have you done?

Check the terminals are still connected? What voltage does the battery read on a volt meter?

 

Everything is clean and secured. I haven’t tested anything yet but I got rescued with a jump tonight. Alternator? I’ll update in the morning

 

took the new battery to get tested just to check, it was good. picked up a new alternator, swapped it out, still nothing. All day it hasn’t been able to jump start, a new alternator made no difference.
any ideas?????

 

You need to up your troubleshooting game. If the battery tested good what logic was used to replace the alternator?? The alternator functions once the car is running, not to get it running. You probably have a failed starter solenoid resulting in no crank.

However, you mention in the OP your instrument cluster and radio is black/none functional. This has nothing to do with the starter but other electronics. Polarity reversed when installing new battery? Yet you do say the car ran initially. <shrug>. Start checking your fuses, both in the car and under the hood.

 

if the car starts off of a jump, runs until I get home then won’t start again, that would be the logic. I’ll look into starter solenoid

 

Once started, a engine will run using the alternator alone. The battery is mainly only for starting the engine. If the engine was running off battery alone, the idiot light on the cluster would illuminate and the car would eventually die. Likely your original alternator was just fine and didn't warrant replacing. You live and learn...

Being your car goes completely dead the moment you shut the engine off, indicates a battery issue- whether it be the cables, fuses, fusible links, connections, relays, etc.

Check the starter connections as some cars have had issues with bad/ corroded hardware which would result in a no crank situation. Also, check over all of the connections at the battery (especially the positive (red) terminal) and nearby connectors: this forum member had a issue with a melted connector.