No signal on my nexus 5

Did you buy the phone new? Or second hand? If second hand make sure to check if the IMEI # is clean and not blacklisted.

I dropped my phone quite a few times.

For me it was the sim card...... I am a verizon customer. No cost to fix for me. It's worth it to check out.

Some symptoms were shutting off sporadically, Camera malfunctioning, Lots of dropped calls with a power down following.

Good luck

My phone is not working can't call out or put apps on

Was having problem with dropped calls was antennas you need to undo them clean with IPA and snap securely should notice difference.

Good luck

You may also need to backup and reset phone.

After upgrading Nexus 5 from Android 5.1.1 to 6.0.1 cannot make outgoing phone calls or receive any calls as "No SIM card - No service" message, even though SIM card works on other phones.

Please let me know if anyone has the solution to this.

Thanks!

These phones are pretty straightforward what I have found is that the antenna gets knocked loose very easily and maybe the new os is more finicky about signal strength. If you have dropped or bumped your phone it will pop off the antenna connector but stay connected enough for use but it will drop calls show no or very weak service signals.

Easy to pop off back to check antennas just resent.

There is a guide on fixing site.

May not solve your problem but yah gotta start somewhere.