Profilux PlusII firmware problem

Hi, I have a Profilux Plus II that has a possible firmware problem.
I have tried the Flash firmware utility which installed correctly, on power up the screen displays 'check ok' up to the Profilux logo.
However there is no key functionality at all, when connected to Profilux control there are no Temperature or pH sensor tabs available in 'Probe/sensor controls'
Furthermore the serial number for the unit reads as -1 which is incorrect.
I have installed Firmware version 5.15.
Can you suggest what might be the problem and how I can fix it?
Many thanks
Mick

Have you try another FW update by using flasher tool?

@Techmik: you have a PM.