You can download the latest version of my flasher tool here:
Remember to kill your piservicestarter.exe, piservice.exe and piserver.exe before running the flasher tool !! Otherwise it won’t work.
For Pimax 4k, it will only work with serial starting with 100. For 5k/8k no restrictions apply.
First kill the the above executables from running, with your task manager (piservicestarter from within the services tab). Then click "enter dfu mode’. Once your headset is in DFU mode (leds will be flashing) you can then click “flash FW”, it will ask for a FW file and then flash it.
Reboot PC after you’re done.