A friend hooked up my battery with negative polarity and blew 4 different fuses replaced all fuses but now just get a click when attempting to start. Do you think it’s a relay how should I diagnose further any help appreciated

 

Oof... that can do a LOT of damage. There are a lot of sensitive electronics / computers in a modern vehicle, and they don't do well when they're hooked up backwards. It could have fried a lot of different things. I would start by checking every fuse in the vehicle. Beyond that, I'd try to hook up an OBD reader to see if it's trying to tell you anything.

But be prepared for a long, ugly process to try to get it corrected. It could have literally totaled the car.

 

I dont know how it is even possible given that the clamps are different in diameter for exactly this reason.

 

perhaps they were using jumper cables. That said, OP needs to check all fuses (some may not be in the main box), relays and look for burnt wires. Some models also have a fuse on the power lead to the starter that should be checked. Sounds like the starter solenoid is clicking which says its getting some power, so its possible they now have a flat battery.

 

It does sound like a bad battery. Clicking usually means low voltage reaching the starter solenoid. Check your battery voltage while trying to start it. If it drops to 8 or 9ish volts then the battery is low. If it stays 11-12ish volts then check the battery cables for continuity and resistance.