This is coming up a few times now and always linked to another site for the answer, so I felt it's best I post it here too.
Method One
Can fix false alarm warnings, and failure to shut down or start &/or charge, but it may only be available when the car detects a problem.- Disable "Keyless Entry" in the touchscreen (behind the steering wheel) under "Doors & Locks".
- Get settings mode ("gear" icon) on the speedometer screen, with the left/right arrows on the wheel.
- Press the brake AND start button for 30 seconds. A new menu appears: "shut off".
- Follow onscreen instructions. It asks twice to keep the OK button & brake pedal pressed until the displayed countdown bar finishes.
- After shut-down, wait 5+ minutes. Then it should work normally & you can reset Keyless Entry.
- If it still doesn't work, try starting the car to "ready" mode, wait 5+ seconds, then turn it off, get out & lock it, wait 5+ minutes, then restart 5 sec, off 5 min, etc. 10 cycles will sometimes clear false alarms.
- If it still doesn't work, go back to step 2 but leave it shut down as long as possible (30+ hours nearly always works in a 2019, but once when that failed 61 hrs. worked).
Method Two
If that doesn't work, & you're stranded with a non-working car, you might try the @IanML 12V reboot.- Leave the bonnet open, along with a door or the left window (for headlight switch access), & wait 5 min for sleep mode.
- Disconnect the 12V & wait 5 min for the system to depower.
- Reconnect the 12V, wait 30 seconds & without opening or closing any door, hatch, or hood, turn on the headlights. Now you’re good to go.
