Vortex

I was out for a few flights last night with my JJ1400 in the Boomerang, and on the first start attempt it failed which is unusual as it very rarely does apart from cold gas etc. But the funny thing was the display showed your 64200 well more a flicker between 64200 -64600 it never showed a start bad message or made any attempt to spin the turbine again.

I switched off and tried again, I heard the glow plug tone then again the rpm figure flickered around 64K.

I did have the turbine out as I have been playing around with pre load.
I have my Glow Plug wires down one side and the RPM/EGT down the other, and I have about 6 flights since I took out the wren so know it was ok before. Glow plug wires are twisted or twitched as the call it in Aus (sorry BJ could'nt resist).
But I may have had the wires closer together this time, I did also have the glow plug wires cable tied to one leg of the starter housing.

So I snipped of the cable tie and pushed the wires back as far as I could to the sides, tried again then got a series of glow bad messages so after replacing the plug I decided to top up my ECU battery as I have suspected this battery in the past as getting a bit iffy if was charged the day before flying, needs to be charge before each flight.
I am using a jetcat 6 cell 1200mah Nicad in the Boomerang, and used a 2 cell lipo 1000mah in the bobcat which I charged every flight.

It then fired up as normal once I topped up the battery and replaced plug, moved wires etc.

The reason I am mentioning all this is, I got the same message as you, but not sure why but this is what I did and it went away.

Separated the glow wires as far as possible to the RPM wires
Fully charged my Battery,
Replaced the glow plug, (as the glow bad messages made me suspicious)
Un plugged/plugged in and out my Rpm cable (I have it on an extension) as it had been disconnected when I removed turbine.

I would try the above with one extra, try another battery. When I first got my turbine and new nothing I had endless problems getting it to start, when I went to a friend who new more about turbines, he fitted a different battery to save waiting on mine to charge and our problems were solved.

Fit a new plug, and make sure the contact is also very good, especially if using the booted connector, I once had a series of glow bad messages caused by the spring in the connector sticking.