Recently solved issue with update of Phantom 4 pro+ remote. During update of software it became stuck in loop where upon boot up the phrase "unfortunately the DJ 4 app was forced to close". After clicking ok, still could not access any part of menu and the message would return. Tried a reset suggested on anther post that involved holding C1, C2 and shutter button during startup which did seem to affect the startup (power light was blue instead of red) and may be useful for other situations but did not solve my issue. Most posts deal with stand alone devices that have more reset options.
However, simply pushing the small button on top of screen after clicking "okay" as above allowed me to access menu and reset factory from the main menu. It looks like a phone power button, but is not used in usual operation of the pro+ so I had not even noticed it. In normal operation, it appears to turn off the screen, but I haven't tested significantly.
Since I did not find this answer after a fairly extensive search of posts and wider net, I thought it was worth sharing.
However, simply pushing the small button on top of screen after clicking "okay" as above allowed me to access menu and reset factory from the main menu. It looks like a phone power button, but is not used in usual operation of the pro+ so I had not even noticed it. In normal operation, it appears to turn off the screen, but I haven't tested significantly.
Since I did not find this answer after a fairly extensive search of posts and wider net, I thought it was worth sharing.