Received my VNA2 from the recommended shop.
Two issues:
1. The battery holder did not fit my 18650 battery, too short ( or he battery toolong ..)
2. Powering up by USB the screen flashed at (almost) regular intervals, no text or graphics.
I had no problem entering DFU mode and flashed the latest firmware (several times)
The flashing initially persisted but now the screen is half-dimmed white.
I'm at a loss.
Any suggestions, anyone?

73 de LA6GH
Nils

The screen flashing means the USB port is not supplying sufficient power. Try a phone charger or power bank.
Battery needs to be unprotected flat top 18650 cell. See website for pictures of what it should look like.

https://www.tindie.com/products/hcxqsgroup/4-nanovna-v2-plus4/
Scroll down to where it says "battery".

If you flashed 20201013 firmware and it does not boot up, you may have a newer hardware revision that requires the later 20210726 firmware: https://nanorfe.com/downloads/20210726/nanovna-v2-20210726-v2plus4.bin

I also had this problem with mine, It takes a full charge battery to run, or a high current wall wart to provide the current needed.
I hope that is all you have wrong!

Thank you to all that responded with suggestions.
Unfortunately nothing helped and my unit is still dead as
a doornail, guess I must now complain to the
seller/manufacturer.

Brgds
Nils

After inserting new battery mine did not come on. So I connected the USB cable and it came on! Once the USB cable was removed it worked fine.. it's there in the manual in the files section I think!

Good Luck!
Raj vu2zap

Problem solved.
The manufacturer adviced me that the 20201013 version is
not compatible with the latest hardware. The experimental
20210726 did the trick, I'm now proceeding to explore my
new toy!

Brgds
Nils