PixHawk 4 Mini PX4IO not found

I am unable to get my recently purchased PixHawk 4 Mini to connect to my FrSky X4RSB receiver. I have tried the receiver in CPPM mode connected to the PPM port and SBUS mode connected to the RC IN port. In each configuration the QGroundControl app reports detected 0 radio channels. I tried a second receiver of the same type from another model and I had the same problem. I double checked the pinouts for both devices, it is wired correctly and is using the cable provided in the box. This is proven by the devices properly power up and the receiver is able to bind to the transmitter. I updated the firmware to the latest stable without any change. After some digging online I found that this usually means the IO board is not working. I checked the logs on the SD card and found this:

PX4IO update failed
PX4IO not found
ERROR [init] Failed loading mixer: /etc/mixers/quad_x.main.mix

So it looks like something is wrong with my flight controller. Can you guys help me out with this? Do I need to request an RMA for this flight controller? Thanks for any help in advance.

Good day,
did you try to push the safety switch while booting your fc?

Good day,

Thank you for the reply! I have tried that a couple times by pushing the button on the GPS module while plugging in the USB to the computer. I could not discern a difference once it booted. What does pushing the button during boot do? I read somewhere it was supposed to put the flight controller into some more for updating the firmware.

I contacted support at holybro with a similar issue. They told me to install the stable firmware at ardupilot for the PH4-mini which I did through Mission Planner. This did not directly fix my issue as I was not able to get my FrSky receiver to communicate with the flight controller via the RC IN port using SBUS protocol. I was able to get things going via the PPM plug and PPM mode on my receiver.

If you need the link to either of those things please private message me since the garbage forum will not let me post the direct links.

Using master version of PX4 seems to allow connectivity of the radio. Pixhawk 4 mini and X8R Not working

Hi, could you send the links to me?
I am facing the same problem, albeit with the pixhawk 4.

Please check the wire of your radio receiver with the pinout of the pixhawk. Probably you have to change the position of sbus out pin. I had the same problem.