Radio stuck on interrupt setting. No Bluetooth type device attached or in use. Occurred after car battery was accidentally drained quite low.

Try to reset to factory reset through RESET button on device. Normally it's the POWER button. Press and hold the power button for approximately 10 seconds, your device will reboot.

Keep disconnect the car's battery for a longer period of time to ensure that the radio's memory is fully cleared. Be sure to have the car's security code on hand, as it may be required to reactivate the radio after reconnecting the battery.

If none of these steps work, there may be an issue with the radio's hardware or software that requires professional repair. It's best to have a qualified mechanic or car audio technician diagnose and repair the issue.

you can sometimes set the other bluetooth devices to be discover able . If you don't the phone won't see the devices via bluetooth .
Sometimes when you put a device in pairing mode it is making its self discoverable other times you have to set it to be discoverable and then put it in pairing mode.

Bluetooth is a low power radio system that connects devices together.
Say you had taken a photo on your phone well with a computer paired to your phone via bluetooth you can share the file via blue tooth to the computer via the radio link blue tooth system.

If you had a bluetooth hands free system in your car you could pair it with you phone and use it with the phone .

It may just be a short in the wirering

The problem is in the radio. If this is what you want to do find the power to the radio and run it through an on and off switch.

The FCC requires that most of the consumer wireless devices operate on a specific frequency. Unfortunately, that frequency is not reserved for that type of device. most consumer devices are subject to Radio Frequency Interference.

Or the batteries in your device may be low, and require changing.

Sounds like all of the high drain devices are disabled due to a weak battery. You are still getting dash lights and radio because they are very low drain devices. Try charging the battery to test for now. It could be a failing battery, or your alternator and or voltage regulator could be going out and not charging the system. But first, try to charge the battery, and see if you can start it, if you can, let it run for at least 10 minutes. If your alternator/VR is going out or is already out, you should have a guage, or idiot light telling you that you have low voltage. If its a light, you should see a red battery lit up on the dash, if its a guage, it should be directly in the middle +/- a little. If you are able to run the vehicle for a while with no light coming on, or guage showing low voltage, its safe to say you drained the battery, or it is failing. If its a few years old or more, i'd go ahead and replace it. Hope this helps :)

You need to keep a supply to it. You can buy various devices that plug into your cigar lighter. The quite simply have one of these square 9 volt radio type batteries in them. This keeps power on while changing battery. You could easily make something up with one of these batteries and a couple of leads going to the terminals after loosening the bolts. Be careful though and make sure your wires are secure so the do not come off while wrestling with the battery.
Cheers John

Do you have bluetooth enabled? If you do and you are not using it to connect to a headset or other device, it will drain the battery quicker