Hi I had same issue yesterday - trying to clean my display ended with red/green error..
Trying all tutorials made to exact same point as you [ tried 2 PC`s ].
The problem 0xc000007b [ after solving first error with missing stdfu.dll you probably had -> coping from /oculus/runtime this file is not a fix ! ] is caused by too new version of PiPlay as you definitelly have 2.x, or even 3.x, but @sjefdeklerk made his tool last year, I suppose around V.2017 and since that time Pimax also changed their DLL`s libraries.
All you need is:
1) FIRST downgrade to 1.2.x [ _flash tool_ will work ! ]
2) put into DFU mode [ 1) unplug Pimax usb/hdmi, push and hold 3 buttons, plug USB only, wait 8s, release power holding other two for 8s, then release middle, wait 8s, and release last one - clicking it, or option 2) click enter DFU mode in App ]
3) upgrade FW
3) have fun with Pimax [ not asking @support without TeamViewer13 session required, they have a lot of work on 8K trying to hold the promised Q2 shipment ]
Best regards !