NuPhy Air75 V2 - firmware upgrade & troubleshooting

I recently wanted to upgrade the firmware on my Nuphy Air75 V2 keyboard to version 2.1.0 and have encountered all sorts of problems.... Therefore, I would like to briefly describe how to deal with them.

Upgrade instructions

Important notes

You need to update all, the keyboard firmware (QMK), the dongle firmware and the RF firmware, otherwise they will not connect.

Instruction

The official instruction can be found on NuPhy's site

The basic instructions for upgrading the firmware are as follows:

1. Download QMK Toolbox

Download QMK Toolbox from https://github.com/qmk/qmk_toolbox/releases and install it.

2. Upgrade QMK firmware

Follow the official instructions.

In short:

The following steps must be done in the exact order and manner as instructed, if your keyboard is already connected, unplug it before starting the process.

1. Download the firmware from NuPhy's firmware page: QMK_firmware_nuphy_air75_v2.1_ansi_v2.1.0.bin.
2. Start QMK Toolbox and locate the firmware file (ending with .bin) using the Open dialog in the File menu.
3. Set the keyboard to wired mode.
4. Unplug the keyboard
5. Press and hold the Esc key while connecting your keyboard to the PC using the cable that came with your keyboard.
6. Release the Esc key when you see the yellow text in the QMK Toolbox
7. If you have installed all required drivers and they are up-to-date, there are no warnings in QMK Toolbox and the Flash button is enabled, you can press the Flash button to start the firmware upgrade.
8. If you encounter any problems, see the Troubleshooting section below.

3. Upgrade Dongle Firmware

Follow the official instructions.

In short:

1. Download the file dongle_52820_upgrade_v2.1.0.exe.
2. Make sure the USB dongle is connected to your computer,
3. Run the exe as administrator.
4. Click the Start button
5. When finished, click the Finish button
6. Done.

4. Upgrade RF Firmware

You need iPhone or Android phone.

Follow the official instructions

In short:

1. Download the nRF Connect for Mobile App.
2. Save the compressed firmware NUPHY_RF_OTA_Vx.x.x.zip to your phone.
3. Power up the keyboard in wired mode (make sure the connection mode switch is set to WIRED). Press FN+[ to reset the keyboard to factory defaults.
4. Refresh the device list in the nRF Connect application until you find the DfuTarg device.
5. Connect to the DfuTarg device.
6. Tap the Open Document Picker button, locate the NUPHY_RF_OTA_Vx.x.x.zip file saved in step 2, once the file is loaded
7. Touch Start.
8. When the upgrade has finished successfully, power the keyboard off and on again to complete the upgrade.

Troubleshooting

These are the problems I've had and was able to fix with the provided solutions I had to google and found on forums.

Step 2 - Missing WinUSB driver

Problem: In Step 2 you are using Windows and QMK Toolbox displays the following warning message:

STM32 DFU device has NO DRIVER assigned but should be WinUSB. Flashing may not succeed.

Solution: You need to install the driver installer from https://zadig.akeo.ie/ and then install the driver.
Start the Step 2 again

Step 2 - Can't connect to USB dongle

Problem: The Step 2 has finished successfully, but your keyboard can't connect to the USB dongle (but it can connect via Bluetooth) - it has stopped pairing with your USB dongle.
Solution: You need to update all, keyboard firmware (QMK), dongle firmware and RF firmware, otherwise they will not connect.

Step 4 - Unstable connection to dongle (typing characters repeats)

Problem: All steps have been completed successfully, but after connecting to the USB dongle, the keyboard can connect, but typing characters is delayed or repeated several times.
Solution: Re-pair all wireless connections after the update: Once the firmware update is complete, it's important to force re-pair your wireless devices. To do this, hold down Fn+4 until you see the green light blink quickly, then insert the dongle.
Make sure you press the buttons first and then insert the dongle for the pairing to work correctly.

Step 2 - Flashing failed - keyboard is dead

Problem: In Step 2 the flashing failed and the keyboard is dead, no lights on the keyboard, PC doesn't recognize it anymore, nothing happens.

Solution: There is a reset button under the CAPS key. If you press it and reconnect the USB-C cable, it will go into bootloader mode. Then open QMK Toolbox and flash the new firmware from the Nuphy website.