WARNING !! THERE ARE NOW 2 VERSIONS OF THE PIMAX 4K OUT THERE. ONLY USE THIS TOOL IF YOUR SERIAL NUMBER STARTS WITH 100 (SEE STICKER UNDERNEATH YOUR HEADSET)
I wrote my own upgrade tool, I think it works much better than the orginal tool that was posted on this forum. You can download my flashtool here:
The original fails when there are spaces or non-English characters in the fw directory or name. My tool doesn't have that problem. Besides it just works better in general (it's multithreading so it doesn't 'hang' the app while doing stuff)
Remember to kill your piservicestarter.exe, piservice.exe and piserver.exe before running the flasher tool !! Otherwise it won't work.