ADB stops working followed by failed unbricking

SKA

I’m having trouble recovering a couple voxl2 minis (M0104). Here’s what I observed and tried so far:

The minis were working normally on a reliable power supply.
Minor issues occurred (in one case voxl-camera-server segfaulted, in another I tried a custom binary). This may not be relevant.
Units continued to boot normally for 3–4 power cycles.
On the 4th or 5th restart, they stopped booting:
- LEDs show D1 + DS2 solid immediately.
- Sometimes they briefly show D1 + D2 solid before going back to D1 + DS2.
- Tried adb in those rare instances where D1 + D2 were on, didn't work
Tried powering with nothing connected, same result.
Tried unbricking procedure:
- Board recognized as a QDL device (web UI and lsusb both show the QDL device).
- Attempting “Flash Flat Build” with VOXL2 QDL Image 14.1a_1.7.8 always times out.
- I couldn’t find a voxl2 mini specific flat build, and in the latest voxl2 mini SDK there's no ufs directory as described here

My questions:

Is there a separate QDL flat build for the voxl2 mini (M0104), or should the standard voxl 2 flat builds work?
Since I’d prefer to recover data if possible, is there any way to get the board into fastboot or ADB without reflashing?
Does the LED pattern (D1+DS2 solid, sometimes briefly D1+D2) indicate anything specific about the boot state?

Any help would be greatly appreciated, thank you!

Vinny

Hi @SKA
Apologies no one responded promptly.
From what I gather, these are best to be sent back as an RMA and we can try to recover them.

D1 (green) is an indication of the local 3.3V power being Good. So, that implies you have 3.8V input, and the 3.3V reg is OK.
DS2 (RGB) is controlled by Qty-3 GPIOs from the SoC. This can briefly blink on boot until the GPIOs are configured by apps software.
D2 (green) is the 5V USB VBUS USB1 (10-pin) port power indicator, which only comes ON after the QRB5165 boots and Apps controls the GPIO to turn the VBUS ON.

On failed SW loads, it is common to diagnose that by seeing DS2 or D2 blink, which indicates boot loops. D1 should NEVER go off, if so, something is wrong in HW or cabling.

We do caution any customer that sets up their own CI or internal validation automation to include a nice pause before repeated power cycles. A common 5 second rule is good to let the large caps discharge, or certain ICs will never fully reset. This is the most common cause of "bricking" devices.

The RMA is your best bet here and we can try to recover them for you, or diagnose for any other issues: https://www.modalai.com/pages/rma