Recent purchase of Hantek DSO5072P with the specific intention of implementing the 200MHz hack. Having the same problem as Checksum47 on attempt to back up firmware: "Firmware update failed, error 0xfe, No upgrade files detected on USB device"
Model DSO5072P
sw version 3.40.0(180120.0)
hw version 1010xffff8108
UPDATE!
Okay, so maybe I'm not so bright...but...
Thought it might be my USB stick, so I tried another. Same error. So, I tried downloading the latest firmware from Hantek for the 5072P...got a new version 3.40.0(190125.0) and loaded it onto the USB stick. Oscilloscope updated fine. Deleted firmware update file and copied the update tool to the USB stick (as per tinhead's post). This time it completed the update without error, my USB stick has the dump folder, and my timebase now goes down to 2.00ns.