I've had this issue for a while and no idea what is going on.

About 1 in 100 attempts to start the car will give me nothing. Nothing at all turns on (radio, lights, etc). I then need to go to the trunk and disconnect the battery and reconnect it. Then the car starts up fine.

Has anyone else had this issue? Any ideas on what is going on?

It's a 2010 Jag XF 5.0.

Possibly unrelated - The above happened when I was driving the car once per week from 2018-2020. Since covid it has sat for months at a time unused. It always requires a jump now. Even after a jump my radio will reboot while driving at times. I put in a new battery and replaced the ground wire that has the battery monitoring circuit. Now my bluetooth will not connect anymore. One other strange thing that has always existed is the doors will not lock. The car beeps when I click lock on the keyfob, but I can always just open the door and the alarm will go off. I'm not looking to fix all these issue, just to understand the first and thinking some of these could possibly be a clue.

Thanks!
Josh

 

And here is the difficulty in trying to help- what level of mechanical expertise does the OP have ? Often scant information is provided . So kindly forgive me if any or all of the following are just too obvious or seem silly to you...
Battery- are the terminals and cables super clean/polished and terminals tight ? It immediately sound like an intermittent faulty battery connection issue to me or just a dud/undercharged regardless of new or not battery , in the abscence of other data. Is alternator charging ? Is battery showing a good charge ?
Diagnostics- what if any codes ?
Bluetooth- what device does not connect, have you tested other bluetooth devices- do any work- to narrow down the issue ?
doors not locking- are you saying all doors ? Do any or all the doors lock manually ? Do you have keyless entry ? If so , do the doors lock when you press (any) door button
You put in a new battery- does your radio still do its rebooting thing etc ... its not clear from your post... kindly confirm what symptoms are current now you have a new battery apart from bluetooth issue ?
Either way , hope you get it sorted ! These are ( IMHO , unnecessarily so ) complex beasts... but worth it !!!

 

[QUOTE=jferg40;2508162...I put in a new battery and replaced the ground wire that has the battery monitoring circuit.
Josh[/QUOTE]

What was wrong with the existing ground wire. When disconnecting/reconnecting the battery to get going again, the wires are being jostled to complete a circuit that is otherwise hanging by a thread. Ground is most likely root cause, put every thing there back to stock configuration.