micro:bit V2: it is not possible to switch "meet-the-micro:bit" to Bluetooth flash mode

[PSLLSP]

micro:bit V2.21. I noticed for second time that micro:bit V2 flashed with application "meet-the-microbit" cannot be switched to Bluetooth flashing mode. RESET button is ignored, sequence of pressing RESET button 3 times doesn't work and triple action (A+B+RESET) doesn't work too, and board cannot be reset with RESET button, like RESET button was not connected. micro:bit has to be power off and after reset, RESET starts to work again. Could be a hardware issue (some latch is locked) or a firmware issue.

I noticed this behavior on two different micro:bit boards. I do not know how to replicate this state but it sometimes just happens. When it happens, application still runs, buttons A and B could be used to show faces on LEDs, touch button records sounds, etc, just RESET button is ignored...

DETAILS.TXT

# DAPLink Firmware - see https://daplink.io
Build ID: v0257-gc782a5ba (gcc)
Unique ID: 990636020005282039099c59f1333aee000000006e052820
HIC ID: 6e052820
Auto Reset: 1
Automation allowed: 0
Overflow detection: 0
Incompatible image detection: 1
Page erasing: 0
Daplink Mode: Interface
Interface Version: 0257
Bootloader Version: 0257
Git SHA: c782a5ba907377658bc28aa8d132a0fa44543687
Local Mods: 0
USB Interfaces: MSD, CDC, HID, WebUSB
Bootloader CRC: 0x725bea7d
Interface CRC: 0xe561f1de
Remount count: 0
URL: https://microbit.org/device/?id=9906&v=0257

[PSLLSP]

I replicated this issue again. I tried to press RESET button again and again. Faster, slower and in a minute my RESET is ignored... micro:bit runs "meet-the-microbit" program.

[martinwork]

Related: microbit-foundation/DAPLink#21

[PSLLSP]

OK, I see the same. My micro:bit is powered from 3V battery. I tried to power if from USB charger and I can replicate the issue. I can replicate the issue when micro:bit is powered through slot connector. It is not limited to powering from battery connector.

It could happen that micro:bit enters Bluetooth mode with RESET button "disabled"...

I tried other idea. I locked RESET button when micro:bit was powered from 3V battery. Then I connected it to my PC with data USB cable. micro:bit resets on connection and RESET button function is restored; I assume this proves that this is not hardware issue but some glitch in the firmware...

Once I learned the trick, it is not difficult to replicate the issue...