If you have an FW version older than 1.32, you need to first update to 1.32 before you can go higher. It explains this in the
FW update instructions and other places here on the forum.
DJI has historically maintained an archive of FW versions on their site even though they don't always show links to them. For
archived FW versions directly from DJI, follow the links in
this post. They are sorted by Advanced and Pro.
Install 1.32 on your RC, and then afterwards try the current process of using the app to update the RC firmware. As you probably know, the FW version numbers of the AC and the RC do not need to match with current levels of the FW.
Question - which model RC do you have? It's on the sticker in back. Probably either GL300A or GL300B based on the old FW version (1.26) you have now. If I recall correctly, I think that the 300A models could also be updated to 1.4 with a USB stick after 1.32 was installed. Then after 1.4, the 300A was updated with the app only. The 300B model RCs were for sure app only after 1.32 was installed. Keep this in mind.
Important: Since you chose to update FW, I hope that you are aware of the significant flight distance restrictions with the latest FW (1.11.20) that need to be removed. Click
here to read about it, get some of the background, and how to remove the restrictions. Keep this is mind once you get your RC correctly updated.
Also if you are interested,
click here for
some tips that I often share with new P3A/P3P owners. It's getting a bit long, but it has very valuable information.
Good luck!