Just had alternator replaced. Cranked up two times, the second was a struggle. Won’t start now. Tried to jump with cables, there were sparks and smoke. Now ignition is locked and won’t turn. Looking for insight from some infiniti enthusiasts. What could this be? And how pricey to fix

 

Did you ever test your battery prior to replacing your alternator?
Why was your alternator replaced?
Was it bench tested prior to replacement?
If defective it is always preferable to have your OEM alternator rebuilt by a shop that rebuilds alternators, electric motors,, etc.rather than replacing some cheap shyt from China.
Sparks and smoke is indicative of reversed jumper cables or a shorted battery cell.
You can test your battery cells with a battery hydrometer.
Either temporarily remove a good battery from another vehicle to try in your car or just purchase a new battery.
If the vehicle starts measure the voltage across the battery terminals with the engine running.with your multi-meter
A good alternator should be putting out 14.4v
Good luck

 

thank you for the advice! I don’t know much about cars. So the battery and brake light were coming on and I was losing power. Advanced auto said everything was testing fine but then it went out completely. Took it to cheap mechanic for alternator so perhaps it is cheap.

im more concerned about the ignition not turning at all now. How it seems to be locked in place. I moved the gear shift and still nothing. Any idea what that might be?

thanks again!

 

2005 with a push and turn ignition switch? Things need to be powered up to even get that far, like allowing the car to sense the key or the chip in the key to release the ignition switch for example. "Sparks and smoke" may mean you blew one of the LARGE fuses on the "fusible link" which is just off the battery's positive terminal. (Pic below is from '06 FSM but probably the same as yours). Those are like your main circuit breakers in your house and can shut down either all (the 120A fuse) or major parts of the car (80, 60 and 100A fuses). You may need to get some help, like somebody with a volt meter, but I'd start by checking those large fuses.

 

Sparks and smoke means you probably reversed the jumper cables and fried your battery along with electronics. The extent of the damage was hopefully limited to just the negative battery cable and the fusible link but could be MUCH more widespread. Possibly so far as cooking the entire chassis/engine harness and frying the ECM, BCM, and IPDM.

You're lucky it didn't catch on fire and total out the entire vehicle, or explode the battery and cover everything in corrosive sulfuric acid.

Your ignition has a lock cable that goes down to the shift mechanism, probably unrelated to the electrical issues but I can't remember off-hand exactly if there were any electronics attached to it.