Troubleshooting Reinstall Duo

Location of the FEL button on the MOD Duo

Different MOD Duo models
LEFT: older model with nand flash; RIGHT: newer model with eMMC

Troubleshooting section dedicated to the MOD Duo.

A note on different models and old kernel

Please note that there are 2 different kinds of MOD Duo units - older ones with nand flash and newer ones with eMMC.
The new unit models have their name (like "MOD Duo") written and engraved above the right display.

Since version 1.10, we changed the kernel used by the Duo, but this update only automatically applies to new unit models.
For the older models, we need to either do a special update step, or a full factory reset.
In both cases the disk contents (user data) is completely wiped out.

You can check which kernel version you are running by looking at the "System information" in the advanced settings.
Kernel release 5.4.38-rt21-modduo is the newer one, while 3.4.104-rt139-modduo is the older one.
The new kernel offers better performance and reliability, so you are still using the old one please update!

Special update for nand units

NOTE: Only for older MOD Duo units with nand flash. MOD also recommends doing a MOD Duo Factory Reset instead of this special update.

In order to make older MOD Duo units switch to the new kernel we can use a special update file.
This was created mainly for those users who are using Windows or are not comfortable with the command-line.

Please do not power off your unit once the procedure has started!

To begin:

1. Put the unit into recovery mode. See Releases if you need help on that.
2. Download this special update file modduo-convert-nand_20201028.tar
3. Install the tar file in the previous step, and wait until the unit boots itself again in restore mode (this might take a few minutes)
4. Install a MOD factory reset image from the Factory Reset Images section.
5. Wait until the MOD sets leds green and reboots itself

MOD Duo Factory Reset

Requirements: Linux or macOS, basic command-line knowledge
For a factory reset under Windows, see Troubleshooting Reinstall via LiveSuit. (applies only to older MOD Duo units with nand flash)

To begin:

1. Click and hold down the FEL button on the back of the MOD Duo (in tiny hole), while you power it on.
2. Hold it for 2 seconds, then release (The screens will freeze with the MOD logo and name)
3. Connect the MOD Duo to your computer via USB cable
4. Download this file: https://download.moddevices.com/releases/modduo/tools/duo-nand-mainline-factory-reset-v2.tar.gz and extract it
5. Open a terminal and 'cd' to the directory where duo-nand-mainline-factory-reset-v2.tar.gz was extracted, ie:

cd ~/Downloads/duo-nand-mainline-factory-reset-v2

Now simply run:
./boot-fel-factory-reset.sh
(sudo will likely be needed here)

If the above command fails with "USB FEL device not found", try a different usb port of the computer. It might not work with usb hubs or usb-type-c/thunderbolt adapters, so connecting directly to a USB port is preferred..

For non-64bit Linux systems, use the sunxi-fel binary from your distribution.

Continuing:

1. After the script finishes, wait for around 1 minute and the MOD Duo will boot into recovery mode. (confirmed by LEDs turning blue. note that sometimes the display does not change)
2. Install a MOD OS factory reset image.
3. Wait for the installation to complete (the unit will restart automatically).

Note: You can find MOD factory reset images in the Factory Reset Images section.